CRAN is the repository network for R. It is a resounding success with (as of right now) almost 5000 packages, and growth rate which has been estimated (cf John Fox's keynote at useR! a few years ago) to be near 40% per year. We as R community members owe a great deal of thanks to the CRAN maintainers, and the R Core team. The tight integration between the language and the contributed code repository is unique among programming languages, and one of the many reasons why CRAN has been such a success and driver of growth and adoption for R. And the amount of work the CRAN maintainers put into this is substantial, and we owe them. Yet there is some friction between the repo maintainers, and the community of developers. There have numerous discussions on the main developer list about various aspect of how CRAN maintains the impeccable quality of the code in the archive. One particular aspect which has bugging (at least me) is the lack of communication when policy changes are made. It would be trivial to posts a set of changes to the developer list, and I suggested as much. Only to be soundly ignored. But changes to text (or html) files can monitored rather easily, and when such changes occur an alert can be sent. So I cooked up rather simple system for this which I called the CRAN Policy Watch. In essence, a simple cronjob monitors changes, and records new versions in a Github repo (which you can follow or star). Alternatively, the cronjob now also tweets from the @CRANPolicyWatch account which I invite everyone to subscribe to as well. If someone knows of a simple tool to summarize diffs of html or text files in static html pages, I'd be interested to expand the service to some github.io pages. Alernatively I could also just commit to a single file too and let Github summarize the changes. This was an itch I needed to scratch, and I hope some other people will fine this useful too.

This post is just a bunch of random notes, but I think that things are going well, this time.

Btrfs Just started playing with btrfs after converting a 2TB disk with about 1.3TB of data from ext4 to btrfs. This particular filesystem contains my backup data and I hope that btrfs is able to live up to high standards. I will probably write a detailed review with my impressions, but suffice to say that it is working fine and I hope that I will be happy for a long time to come. My other filesystems, for the moment, will be ext4.

Coursera Downloader Thanks to John Lehmann's generosity, now coursera-dl has a new home: a github organization of its own!

youtube-dl Some people may have noticed, others may not, but when downloading videos from Youtube, they apparently are getting more aggressive with the use of Dynamic Adaptive Streaming over HTTP (also called DASH) and, as a result, some (perhaps going to be all in the near future?) of the videos may not be available in the resolution/formats that you used to like (like me, with format number 35). By the way, one thing that is interesting with youtube videos provided via DASH is that they are available in different streams: one for the video and another for the audio. What does this mean in practical terms for users of youtube-dl? Well, if you wanted to download videos in resolutions like the 480p (format 35) that I mentioned, then you will probably have to change your way of doing things, until a more automated solution is in place. You will have to download both the audio and the video and, then, "combine" them (that is, multiplex them) to create one "normal" video file with both the audio and the video. I usually do this via: ffmpeg -i audio.m4a -i video.mp4 -vcodec copy -acodec copy combined.mp4 If you prefer having a Matroska container instead of an mp4 container (which, BTW, results in smaller muxing overhead), then you can use the command line: mkvmerge -o combined.mkv audio.m4a video.mp4 Oh, those m4a and mp4 extensions are a new addition that I just sent upstream (in the past, both would have been named with an extension of mp4). As, an aside, I like formats 135 for video and 140 for audio, for the reasons that I mentioned in a comments to issue 1612:

Otherwise, to download 480p videos (which I do for lectures and so on with other projects of mine, like edx-dl) I have to call youtube-dl twice: once for format 135 and another for format 140, since the old format 35 files are much smaller than the lower resolution 360p files (due to the former being encoded in High profile vs. the latter being encoded in Constrained Baseline profile).

While this is unfortunate for some, this is a good thing for others: I once had a blind user of youtube-dl asking me if he could avoid downloading the whole video just to extract the audio, so that he save on bandwidth. Well, now this is possible. Expect a new version of youtube-dl to be uploaded soon to Debian unstable.

Music It is so nice to see the music that I like getting better. It was particularly pleasant to see Tarja Turunen being joined on stage by Floor Jansen. In fact, it is my impression that the once female-fronted bands are getting more and more into collaborations and side-projects and they are, in many ways, getting more refined. Examples of this includes Floor, Tarja, Anneke van Giersbergen, Sharon den Adel, Kari Ruesl tten and many others that I can't remember right now. Of course, some thanks to people that take the time to film, and upload/share the videos so that other people not at these events can watch them is highly appreciated and they usually are treated as anonymous, but, of course, this should be fixed.

I ve owned a Thinkpad T61 since February 2010 [1]. In most ways it s a great system and it still does most things that I require, even though it inspired my post about how modern laptops suck [2]. Problems with my T61 The biggest ongoing problem with my T61 was the heat production, I m not sure how much of it was due to the CPU producing heat and how much was due to the cooling system not removing it fast enough. But any serious computation for even a relatively small amount of time caused it to get close to thermal shutdown. But as I mostly use my laptop for reading email, a SSH client, and coding (for which the big compiles are done on servers) that didn t force me to replace it. The next problem was the battery life, it s expected that laptop batteries degrade over time so it wasn t a surprise that after 3 years my T61 battery only lasted for about 15 minutes. A final problem is the screen which didn t seem to be as bright as it used to be, it s annoying but doesn t compel me to buy a replacement. T61 Failure But in July my T61 stopped working, it appeared to be either the power supply or something internal related to power, it had been running but was suddenly powered down after being left alone so for some reason power wasn t getting from the wall to the laptop. I initially thought that it was the power supply at fault and investigated the price of a new PSU and a new battery as well. The Lenovo online store [3] charges $71.90 for a new PSU and $113 for a regular capacity battery or $156 for an extended capacity battery (50% more power). So based on the assumption that the PSU was faulty that meant a cost of $185 or $228 (maybe more if postage is included) to get the old Thinkpad going again. I could probably get the parts cheaper from somewhere else, but I m hesitant to buy batteries from sources that aren t reliable in case I get one that s been used. Buying at Auction I ended up buying a refurbished Thinkpad T420 (product ID 4236-J73) from Grays Online [4]. It was refurbished and cost me $306.35 including delivery. $306.35 for a new laptop including PSU was a much better deal than buying a new PSU and battery for $185 or more. It turned out that the PSU wasn t broken (a different PSU also didn t work with it) but then my Thinkpad T61 just started working again, presumably it has some intermittent fault related to power and needed to be replaced anyway (I use my laptop for work and can t have it fail randomly). One significant problem when buying a Thinkpad is that the model numbers aren t specific to the hardware specs. According to ThinkWiki the T420 model ranges from a 2.1GHz i3 to a 2.8GHz I7 CPU, from 160G to 500G hard drive, and has either a 1366*768 or a 1600*900 display [5]. Auction sites almost always specify the size of a hard drive and usually the exact CPU speed doesn t matter much for an auction purchase (2.1GHz is fast enough for most things). But the display resolution is a big deal, in this case Grays had multiple Thinkpads on offer with the same description and the same price so bidding on one with high resolution was quite important. Lenovo has a web site for discovering Thinkpad specs, this is the current link for it (it changes periodically) [6]. At that page you can specify the TYPE AKA PRODUCT ID that is printed on the back of a Thinkpad (and usually included in an auction listing) in the search field that s currently described as QUICK PATH and get all the specifications. Lenovo really do a great job of providing all the details for their products (including ones that were obsolete years ago). But it s unfortunate that their web site sucks, there should be a single URL for such things that s easy to find and they shouldn t use cookies to track which model you are looking at because it makes it really difficult to research two different models. Comparing T61 and T420 I upgraded my new Thinkpad to 8G of RAM because RAM is really cheap. I bought it with 4G of RAM which didn t seem to be quite enough as the hard drive is slow for paging (my desktop with 3G of RAM and a SSD performed well for similar tasks). Now it s running really well, my new Thinkpad is a lot cooler than the old one (not being broken is a good thing). My T420 has a screen resolution of 1600*900 which was a little disappointing initially when going from 1680*1050 (18% fewer pixels and 2% fewer than the T41p I used previously). But having a smaller screen means that the Thinkpad is a lot smaller and lighter. My T61 didn t fit in most backpacks and laptop bags and was unreasonably heavy, it s the type of laptop that looks good on a spec sheet but doesn t seem so good when you carry it around for a few hours. Not only is the T420 a lot smaller and lighter than the T61 but the power supply that shipped with it is a lot smaller and lighter too. I might have spent $72 a few years ago to buy a lighter PSU if I knew that was an option. Cost of Ownership Thinkpads are getting so cheap at auction that I m tempted to buy myself an X series as well. When a $300 item can last several years (my T41p was from some time before 2006, my T61 was from 2010, and my latest is from 2013) that brings the cost of ownership down to something like $0.25 per day. If I bought myself a Thinkpad X series (ultra light) as well at auction then I would be looking at maybe $0.50 per day for my laptop use which would give me the option of taking a light laptop to a conference and a bigger laptop for spending a day at a client site.

• [1] http://etbe.coker.com.au/2010/03/16/thinkpad-t61/
• [2] http://etbe.coker.com.au/2011/09/09/modern-laptops-suck/
• [3] http://shopap.lenovo.com/au/en/laptops/
• [4] http://www.graysonline.com/
• [5] http://www.thinkwiki.org/wiki/Category:T420
• [5] http://support.lenovo.com/en_AU/landing.page

20 months ago I started the LUV Hardware Library [1]. The aim of the project is to provide a repository of free spare parts for computers for the use of club members. People who have parts that are good but which they can t use can donate them and others who need such parts can take them. Some people have criticised my choice of the name Hardware Library because the word is associated with borrowing while with my Hardware Library it is expected that noone will return the item that they take. The Wikipedia page about libraries is worth reading, my interpretation of that is that the essential aspect of a library is that it is a public collection of items that are useful for study and that borrowing is just one thing that can be done. A book library could consist of a service of printing free books on demand (anyone could do this with access to The Gutenberg Project [2] and a printer) or of just making them available to download. Many libraries don t allow books to be borrowed, they just allow them to be studied and copied in the library. Also every general public library has reference items that can t be borrowed, it s typical for a library to have a full encyclopedia which is not available to be borrowed. Also with the Hardware Library people feel obliged to give something if they take something (as happens with a geocache), so there is an issue of returning something. My main aims with the Hardware Library were to save people money on parts and to help the environment by reducing the need to buy new computers when old ones can be upgraded and remain in service. My next aim was to help people learn about hardware by providing free parts, when a mistake has no financial cost people are more willing to experiment and will learn more. I believe that those aims have been achieved. More Successful Than Expected One thing that surprised me is the social aspect that developed. I had expected that most people would just find some parts that they need and not look at it again for some months. I had also anticipated that some people would poll the Hardware Library every month in the hope that a part they needed might appear. I didn t expect that people would look through it every month because they just like looking at old hardware. I also didn t expect groups of people to hang out by the Hardware Library to discuss various issues related to PC hardware and Linux. During the breaks in the main meeting the location of the Hardware Library often becomes a focus for discussions of various issues related to Linux and hardware. I think that this is really advancing the aims of LUV [3] and I think that members of other LUGs should experiment with similar projects. Starting this didn t require any special skill or authority. I just started bringing a briefcase full of parts to meetings and offering them to whoever was interested. Any member of any LUG can do the same. To start something like this you wouldn t even need a collection of parts, you could just bring a box and ask for donations.

• [1] http://etbe.coker.com.au/2012/03/05/luv-hardware-library/
• [2] http://www.gutenberg.org/
• [3] http://luv.asn.au/

Review: Lean In, by Sheryl Sandberg & Nell Scovell

Publisher:	Alfred A. Knopf
Copyright:	March 2013
ISBN:	0-385-34994-7
Format:	Hardcover
Pages:	217

Lean In is normally listed as written only by Sheryl Sandberg, which is also what's on the dust jacket, but the inside cover says "with Nell Scovell." Given what that normally means for celebrity books, supported by comments in the acknowledgments, I'm listing it as co-written by Scovell. However, much of the book is written in the first person and is clearly meant to be Sandberg's voice, so I will mostly refer to Sandberg as the author for the rest of the review. I was unfair to this book. Lean In made quite a splash when it first came out, since the named author is the Chief Operating Officer of Facebook, a former vice president of Google, and one of the most prominent female executives in the business world. The subtitle is Women, Work, and the Will to Lead, and the normal Internet summary was that it focused on how women could change their behavior to be more effective and successful in the business world. Throw in some ridiculous review hyperbole (one New York Times writer compared it to The Feminine Mystique, which is a bit like the comparison of every extruded fantasy product with The Lord of the Rings) and I was ready to hate this book. It's work advice from someone in a very privileged position, and it seemed to have a distinct whiff of victim-blaming. It's obvious, however, from the first few pages that Sandberg was very aware of this trap and had no intent of falling into it. This is hard: giving practical advice to women on how to navigate a sexist culture runs a severe risk of victim-blaming even with the best of intentions, particularly since part of the sexism of the culture is a pervasive impression that women aren't doing enough. But I think Lean In handles that about as well as one could while still writing a book focused on practical advice rather than revolutionary change. Sandberg is clear that many things women can do to help their careers shouldn't be necessary, and she takes some time, in each section, to talk about the shape of any structural unfairness that she's seen. What advice she offers here is clearly in the spirit of how to navigate a system that is unfair and unequal, but which can be navigated and can be made more fair by more women participating. This is a very practical book, with more in common with business self-help books than with feminist critiques. It's also a narrowly targeted book, not that you'd guess this from the number of copies it's sold and the sort of publicity it got. Lean In is advice to female executives about how to navigate the top levels of US business culture, with a strong eye for issues of feminism, gender-based double standards, and potential traps of self-sabotage. It offers a blend of encouragement, practical tips, and some forthright analysis that tries to bring to the surface internalized sexism and perceived barriers and limitations for female executives so that they can be addressed and hopefully overcome. It's not in any way a revolutionary book, either with respect to business culture or with respect to gender roles; rather, it's an open acknowledgment of a whole bunch of problems combined with practical advice for how to work around those problems until they can be solved. For the most part, it doesn't attempt to address how to solve the problems. There is nothing wrong with that as a focus for a book. Lean In has attracted a fair bit of criticism in some circles, but, after reading the book, I think a lot of that criticism is predicated on assuming different goals than this book actually has. Contrary to various glowing reviews, Lean In is not a book that's going to change the world; rather, it's a book that might help a narrow band of the population in a specific job and career path navigate problems of sexism and gender expectations and be more effective. Read in that light, it struck me as honest, open, considered, and well aware of its own limitations. Sandberg says repeatedly that many of the options she discusses simply aren't available to most women, and that women may not be in a position to be able to make the decisions she made. She's quite forthright about the limitations of her own experience and the limitations of the advice that she offers, and I think deserves full points for honesty. Similarly, when it comes to business culture, Lean In is not about changing that culture for the better. It's about navigating that culture as it exists. Here, I think Sandberg is less aware of the limitations of this perspective; there is far less acknowledgment in Lean In that executive culture may be inherently toxic as there is of the limitations that women face in business. But while Sandberg has an obvious blind spot, this is not a paean to overwork. It has some excellent advice about work-life balance, including the need to put strict limits on the amount of time one spends in the office and the necessity for someone to pick up substantial burdens in the home if one of the members of a household is going to pursue a business executive job. I was worried, going in, that Lean In would excuse, justify, or idealize the culture of exploitation so common with salaried jobs in the United States, but it really doesn't. As with feminism, it doesn't pick any deep fights, and those with a "kill it with fire" gut reaction towards US executive culture (such as myself) will find the bland acceptance of it irritating, but this is more of an issue with reader expectations than with the book. One should not expect a highway map to point out that trains are more efficient. So, I'm willing to stand up for Lean In to a degree. This is not a bad book. It's very readable, parts are quite interesting, and some of Sandberg's observations about the intersection of gender expectations and executive culture were worth hearing. I learned some things from it. But I think one should read it in full awareness of its limitations. This is a book of practical advice that will only be of direct use to 10% of the population, and which could be generalized with some effort to maybe 25%. It has little to say to women who are not in white-collar, professional jobs, and its applicability to women who aren't aiming for executive careers is a bit hazy. It's the kind of book that's full of anecdotes about how Sandberg got parking spots reserved for pregnant women at Google by talking to the founders about it, or about how to negotiate salary when offered an executive position, which are vaguely interesting but of dubious practical benefit to people who aren't offered jobs where salary and benefit negotiation is available. This isn't the fault of the book, but at times it is rather stunning how different (and how much more tractable) the world looks to someone with the wealth and personal connections that Sandberg has. (To her credit, Sandberg does seem to be aware of this and does acknowledge it.) If you are a female executive, or a male executive interested in developing your empathy and understanding of how institutional sexism affects your colleagues, I suspect Lean In would be quite helpful. If you're not, I think it's mostly a curiosity. But it's also well-written, well-organized, probably available in most libraries in the United States, and provides anecdotal data to help build a more complete picture of the concerns and experiences of female executives. Unless you're in the specific target audience, I'm not sure I'd recommend going out of your way to find it, but it's probably worth reading if it falls into your lap. Rating: 7 out of 10

The last few days I have been experimenting with the batman-adv mesh technology. I want to gain some experience to see if it will fit the Freedombox project, and together with my neighbors try to build a mesh network around the park where I live. Batman-adv is a layer 2 mesh system ("ethernet" in other words), where the mesh network appear as if all the mesh clients are connected to the same switch. My hardware of choice was the Linksys WRT54GL routers I had lying around, but I've been unable to get them working with batman-adv. So instead, I started playing with a Raspberry Pi, and tried to get it working as a mesh node. My idea is to use it to create a mesh node which function as a switch port, where everything connected to the Raspberry Pi ethernet plug is connected (bridged) to the mesh network. This allow me to hook a wifi base station like the Linksys WRT54GL to the mesh by plugging it into a Raspberry Pi, and allow non-mesh clients to hook up to the mesh. This in turn is useful for Android phones using the Serval Project voip client, allowing every one around the playground to phone and message each other for free. The reason is that Android phones do not see ad-hoc wifi networks (they are filtered away from the GUI view), and can not join the mesh without being rooted. But if they are connected using a normal wifi base station, they can talk to every client on the local network. To get this working, I've created a debian package meshfx-node and a script build-rpi-mesh-node to create the Raspberry Pi boot image. I'm using Debian Jessie (and not Raspbian), to get more control over the packages available. Unfortunately a huge binary blob need to be inserted into the boot image to get it booting, but I'll ignore that for now. Also, as Debian lack support for the CPU features available in the Raspberry Pi, the system do not use the hardware floating point unit. I hope the routing performance isn't affected by the lack of hardware FPU support. To create an image, run the following with a sudo enabled user after inserting the target SD card into the build machine:

% wget -O build-rpi-mesh-node \
    https://raw.github.com/petterreinholdtsen/meshfx-node/master/build-rpi-mesh-node
% sudo bash -x ./build-rpi-mesh-node > build.log 2>&1
% dd if=/root/rpi/rpi_basic_jessie_$(date +%Y%m%d).img of=/dev/mmcblk0 bs=1M
%

Booting with the resulting SD card on a Raspberry PI with a USB wifi card inserted should give you a mesh node. At least it does for me with a the wifi card I am using. The default mesh settings are the ones used by the Oslo mesh project at Hackeriet, as I mentioned in an earlier blog post about this mesh testing. The mesh node was not horribly expensive either. I bought everything over the counter in shops nearby. If I had ordered online from the lowest bidder, the price should be significantly lower:

Supplier	Model	NOK
Teknikkmagasinet	Raspberry Pi model B	349.90
Teknikkmagasinet	Raspberry Pi type B case	99.90
Lefdal	Jensen Air:Link 25150	295.-
Clas Ohlson	Kingston 16 GB SD card	199.-
Total cost		943.80

Now my mesh network at home consist of one laptop in the basement connected to my production network, one Raspberry Pi node on the 1th floor that can be seen by my neighbor across the park, and one play-node I use to develop the image building script. And some times I hook up my work horse laptop to the mesh to test it. I look forward to figuring out what kind of latency the batman-adv setup will give, and how much packet loss we will experience around the park. :)

No, not to this 3.11, but to Linux kernel 3.11.

I was aware of the #718533 bug, which happens when you have a software RAID with anything higher than 3.2.0 (mine is RAID 1 with 2 disks). At least that has been my case since I tried to upgrade, hence I was delaying upgrades again and again.

Unfortunately today things went worse when I tried to plug my USB 3.0 device on the system:

Oct 20 17:52:51 busgosu kernel: [20799.672127] xhci_hcd 0000:02:00.0: Timeout while waiting for address device command
Oct 20 17:52:51 busgosu kernel: [20799.876136] xhci_hcd 0000:02:00.0: ERROR no room on ep ring
Oct 20 17:52:51 busgosu kernel: [20799.876148] xhci_hcd 0000:02:00.0: ERR: No room for command on command ring
Oct 20 17:52:51 busgosu kernel: [20800.080148] usb 2-2: device not accepting address 2, error -12
Oct 20 17:52:51 busgosu kernel: [20800.080202] xhci_hcd 0000:02:00.0: ERROR no room on ep ring
Oct 20 17:52:51 busgosu kernel: [20800.080209] xhci_hcd 0000:02:00.0: ERR: No room for command on command ring
Oct 20 17:52:51 busgosu kernel: [20800.080221] xhci_hcd 0000:02:00.0: ERROR no room on ep ring
Oct 20 17:52:51 busgosu kernel: [20800.080227] xhci_hcd 0000:02:00.0: ERR: No room for command on command ring
Oct 20 17:52:51 busgosu kernel: [20800.080235] hub 2-0:1.0: couldn't allocate port 2 usb_device
Oct 20 17:52:53 busgosu kernel: [20801.568169] xhci_hcd 0000:02:00.0: ERROR no room on ep ring
Oct 20 17:52:53 busgosu kernel: [20801.568181] xhci_hcd 0000:02:00.0: ERR: No room for command on command ring
Oct 20 17:52:53 busgosu kernel: [20801.568190] hub 2-0:1.0: couldn't allocate port 2 usb_device

And of course the device didn't show up. As there's not much relevant stuff about this issue on the googlesphere, thought it may have been solved. And turned out that I was right: upgrading fixes this, and now the device works again.

But, hit by the above bug now I have to add a rootdelay=1 to my kernel boot parameters (started testing with 5 but finally seems one second is enough). Fortunately the Ubuntu folks have detailed how to do it ;-)

Hadn't mentioned yet that I saw Herbie Hancock last Friday at the CSO / Symphony Center. That's about the fourth time I have him according to this blog (September 2007,March 2005, April 2004) and I think I saw him two more times when I lived in France, and maybe once while I was in Canada. This time, the format was a horn-free quintet with Lionel Loueke on guitar, James Genus on bass, Vinnie Colaiuta on drums and Zakir Hussain on tabla. Hancock himself played mostly keyboards / synthesizer, even when he used the full piano as input. Overall the concert was little uneven--Hancock himself alluded to the fact that the five hadn't really practised together. At times they were rolling: the opening was a very rhythmic version of his very old standard Watermelon Man; the encore was a very rocking version of his best-selling pop-fusion hit Rockit. In between, it was sometimes wanting. Still, all five are tremendous artists and I also had a fabulous seat as shown in this Google+ post with a picture of Hancock's setup, including multiple screens. But they did not really connect with audience as a whole, and by the time the encore rolled around, the house was pretty empty.

I wrote the following as part of a post to an discussion forum (I can't remember which one), and people told me that they liked this information and said that others would profit from it if I posted it on my blog, which I now decided to post. The context: for homework of one MOOC, people were trying to download a large virtual machine image that was offered both via an official HTTP source, which was slow. A person volunteered that already had downloaded the image volunteered to create a bittorrent to help fellow students. Other students started saying that the bittorrent download was faster up to a certain point and, then, things slowed down a lot. Of course, they got faster to the point where lots of pieces were already well distributed and, then, only the everybody had already downloaded things and, then, only the seeder had the missing segments of the torrent. Then I commented with:

---

Depending on your bittorrent client, you can add the original HTTP download as a "Web seed" and, this way, your client will download both from the peers and also from the web to fill in parts that are not yet available. One such client is the Free (as in Freedom) qbittorrent, but I guess that others also have this option.

---

Soon after that, people started downloading things much faster.

Follow me on Identi.ca or Twitter The new version of Brebis Chevillette 0.7 was published two days ago. Brebis is a fully automated backup checker. Brebis does not create backups. It only performs controls on them. Brebis is able to detect a corrupted archive compressed with different formats, automatically checking the integrity of your archives and lots of parameters of the files inside these archives or inside a tree of files and provide detailed reports if unexpected states are detected. Check out the list of the supported features. What s new? The main features of this new version are:

• new option -G or gen-full to generate from you archive (or from your tree of files) the configuration file and the list of files you need to run Brebis.
• new parameter target to check the target of a link

Complete example of installing, configuring and running Brebis How to install from your package manager Brebis is available in Debian, FreeBSD, Archlinux and Frugalware. Use your favorite package manager to install it. How to install from the sources

# wget http://brebisproject.org/attachments/download/8/brebis-0.7.tar.gz
# tar zxvf brebis-0.7.tar.gz && cd brebis-0.7
# python3.3 setup.py install --install-scripts=/usr/bin
# mkdir /etc/brebis

What you need before running brebis Our goal is to check on a regular basis the archive /backups/monthly-backup.tar.gz. Brebis needs two files in order to correctly run: a configuration file with general parameters and the list of files with all their parameters. Don t be afraid, both of theses files will be generated by Brebis with the following command:

# brebis -G /backups/monthly-backup.tar.gz
# ls /backups/
monthly-backup.tar.gz monthly-backup.conf monthly-backup.list

All the files inside your archives have been detected and their names and parameters (uid, gid, mode, md5, ) have been written in the file monthly-backup.list. More information about those files. How to configure Brebis Lets save /backups/monthly-backup.list in /etc/brebis: # mv /backups/monthly-backup.list /etc/brebis For /backups/monthly-backup.conf, we just modify the files_list parameters:

[main]
name=monthly-backup
type=archive
path=/backups/monthly-backup.tar.gz
files_list=/etc/brebis/monthly-backup.list

We also save monthly-backup.conf in /etc/brebis: # mv /backups/monthly-backup.conf /etc/brebis Use Brebis Using Brebis is as simple as: # brebis -c /etc/brebis/ -l /var/log/brebis.log If there is not any difference between the current state of your backup and your list of file, the logfile /var/log/brebis.log will be empty. If any difference happens, they will be reported in /var/log/brebis.log. Show time. I m modifying the md5 hash sum of a file in /etc/brebis/monthly-backup.list, during the next run of brebis, I get the following content in brebis.log:

WARNING:root:1 file with unexpected hash while checking
/backups/monthly-backup.tar.gz:
WARNING:root:toto/titi hash is ce4f8cacd8fc702bdd03531b9447818b.
Should have been ce4f8cacd8fc702bdd03531b94478184.

As you can read, Brebis reports a difference between what was expected and what it checks. Now it s easy to do the same for any backup you want to check on a regular basis. Just add something like the next line in /etc/crontab: 01 00 * * * root brebis -c /etc/brebis/ -l /var/log/brebis.log A brebis run will happen every day at midnight to check your backup. Every configuration files in the directory /etc/brebis/ will be inspected. Feedback about Brebis We at the Brebis Project welcome any feedback about Brebis. Feel free to subscribe to the Brebis-users mailing list, by Twitter or email me directly at carl.chenet@brebisproject.org

Official website: http://www.brebisproject.org
Mailing-list: http://lists.sourceforge.net/lists/listinfo/brebis-users

The last few days I came across a few good causes that should get wider attention. I recommend signing and donating to each one of these. :) Via Debian Project News for 2013-10-14 I came across the Outreach Program for Women program which is a Google Summer of Code like initiative to get more women involved in free software. One debian sponsor has offered to match any donation done to Debian earmarked for this initiative. I donated a few minutes ago, and hope you will to. :) And the Electronic Frontier Foundation just announced plans to create video documentaries about the excessive spying on every Internet user that take place these days, and their need to fund the work. I've already donated. Are you next? For my Norwegian audience, the organisation Studentenes og Akademikernes Internasjonale Hjelpefond is collecting signatures for a statement under the heading Bloggers United for Open Access for those of us asking for more focus on open access in the Norwegian government. So far 499 signatures. I hope you will sign it too.

I've been using disk encryption (via LUKS and cryptsetup) on Debian and Ubuntu for quite some time and it has worked well for me. However, while setting up full disk encryption for a new computer on a RAID1 partition, I discovered that there are a few major problems with RAID on Ubuntu.

My Setup: RAID and LUKS Since I was setting up a new machine on Ubuntu 12.04 LTS (Precise Pangolin), I used the alternate CD (I burned ubuntu-12.04.3-alternate-amd64+mac.iso to a blank DVD) to get access to the full disk encryption options. First, I created a RAID1 array to mirror the data on the two hard disks. Then, I used the partition manager built into the installer to setup an unencrypted boot partition (/dev/md0 mounted as /boot) and an encrypted root partition (/dev/md1 mounted as /) on the RAID1 array. While I had done full disk encryption and mirrored drives before, I had never done them at the same time on Ubuntu or Debian.

The problem: cannot boot an encrypted degraded RAID After setting up the RAID, I decided to test it by booting from each drive with the other one unplugged. The first step was to ensure that the system is configured (via dpkg-reconfigure mdadm) to boot in "degraded mode". When I rebooted with a single disk though, I received a evms_activate is not available error message instead of the usual cryptsetup password prompt. The exact problem I ran into is best described in this comment (see this bug for context). It turns out that booting degraded RAID arrays has been plagued with several problems.

My solution: an extra initramfs boot script to start the RAID array The underlying problem is that the RAID1 array is not started automatically when it's missing a disk and so cryptsetup cannot find the UUID of the drive to decrypt (as configured in /etc/crypttab). My fix, based on a script I was lucky enough to stumble on, lives in /etc/initramfs-tools/scripts/local-top/cryptraid:

#!/bin/sh
PREREQ="mdadm"
prereqs()
 
     echo "$PREREQ"
 
case $1 in
prereqs)
     prereqs
     exit 0
     ;;
esac
cat /proc/mdstat
mdadm --run /dev/md1
cat /proc/mdstat

After creating that file, remember to:

1. make the script executable (using chmod a+x) and
2. regenerate the initramfs (using dpkg-reconfigure linux-image-KERNELVERSION).

To make sure that the script is doing the right thing:

1. press "Shift" while booting to bring up the Grub menu
2. then press "e" to edit the default boot line
3. remove the "quiet" and "splash" options from the kernel arguments
4. press F10 to boot with maximum console output

You should see the RAID array stopped (look for the output of the first cat /proc/mdstat call) and then you should see output from a running degraded RAID array.

Backing up the old initramfs If you want to be extra safe while testing this new initramfs, make sure you only reconfigure one kernel at a time (no update-initramfs -u -k all) and make a copy of the initramfs before you reconfigure the kernel:

cp /boot/initrd.img-KERNELVERSION-generic /boot/initrd.img-KERNELVERSION-generic.original

Then if you run into problems, you can go into the Grub menu, edit the default boot option and make it load the .original initramfs.

Hacker News is a fairly influential link aggregation site, with stories submitted and voted on by users. As explained in the FAQ, the ranking of stories is roughly determined by the number of votes divided by a function of the time since submission. It's not a huge traffic driver (my personal experience of stories on the front page is on the order of 30,000 hits), but it's notable because the demographic tends to include a more technically literate and influential set of readers than most other sites. The discussion that ensues from technical posts often includes meaningful feedback from domain experts. Stories that appear there are likely to be noted by technology workers, especially in the Silicon Valley startup field[1].

That rather specific demographic appears to correlate with other traits. There's a rather more techno-libertarian bias on Hacker News than on most general discussion forums, which is consistent with the startup-oriented culture that it springs from - the desire to provide disruptive solutions to real world problems tends to collide with existing regulatory frameworks, so it's unsurprising that a belief in individual rights and small government would overlap with US startup culture. There's a leaning towards the use of web technologies rather than traditional client applications, which matches what people are doing in the rest of the world. And there's more enthusiasm for liberal open-source licenses over Copyleft licenses, which makes sense in a web-focused environment (as I wrote about here).

Now, personally I'm a big-government, client-app, Copyleft kind of person, but for the most part I don't think the above is actively dangerous. It's inevitable that political views will vary, we'll probably continue to cycle between thick and thin clients for generations and nobody's ever going to demonstrably prove that one licensing model deserves to win over another. But what is important is that the ongoing debates between these opinions be driven by facts, and that it remain obvious that these disagreements exist. As far as technical (and even political) discussion goes, Hacker News doesn't seem to
have a problem with that. Disagreeing with the orthodoxy is tolerated.


This seems less true when it comes to social issues. When a posting discussing the myth of the natural born programmer[2] hit the front page, the top rated comment is Paul Graham[3] off-handedly discounting the conclusions drawn. The original story linked to a review of peer-reviewed scientific research. Graham simply discounts it on the basis of his preconceptions. Shortly afterwards, the story plummeted off the front page, now surrounded by stories posted around the same time but with much lower scores.

How does this happen? There's two publicised methods which can result in stories dropping down the order. Users with high karma scores (either via submitting popular stories or writing popular comments) are able to flag submissions, and if enough do so then a negative weighting is applied to the story. There's also a flamewar detector, a heuristic that attempts to detect contentious subjects and pushes them off the front page.

The effect of both is to enforce the status quo of social beliefs. Stories that appear to challenge the narrative that good programmers are just naturally talented tend to vanish. Stories that discuss the difficulties faced by minorities in our field are summarily disappeared. There are no social problems in the technology industry. We have always been at war with Eastasia.

This isn't healthy. We don't improve the state of the software industry by hiding stories that expose conflicts. Flamewars don't solve problems, but without them we'd be entirely unaware of how much of a victim blaming mentality exists amongst our peers. It's true that conflict may reinforce preconceptions, causing people to dig in as they defend their beliefs. However, the absence of conflict does nothing to counteract that. If you're never exposed to opinions you disagree with, you'll never question your existing beliefs.

Hacker News is a privately run site and nobody's under any obligation to change how they choose to run it. But the focus on avoiding conflict to such an extent that controversial stories receive less exposure than ones that fit people's existing beliefs doesn't enhance our community. If we want to be able to use technology as an instrument of beneficial change to society as a whole, we benefit from building a diverse and welcoming community and questioning our preconceptions. Building a social echo chamber risks marginalising us from the rest of society, gradually becoming ignored and irrelevant as our self-reinforcing opinions drift ever further away from the mainstream. It doesn't help anybody.

[1] During the batch of interviews I did last year, two separate interviewers both mentioned a story they'd read on Hacker News that turned out to have been written by me. I'm not saying that that's what determined a hire/don't hire decision, but it seems likely that it helped.
[2] The article in question discusses the pervasive idea that some people are inherently good programmers. It turns out that perpetuating the idea that some people are just born good at a particular skill actually discourages others from even trying to learn it, even those who are just as capable.
[3] One of the co-founders of Y-Combinator and creator of Hacker News.

(Edited to fix a footnote reference)

comments

Today is Ada Lovelace Day:

"Ada Lovelace Day is about sharing stories of women - whether engineers, scientist, technologists or mathematicians - who have inspired you to become who you are today. The aim is to create new role models for girls and women in these male-dominated fields by raising the profile of other women in STEM". source

To celebrate, we asked to some of the "women behind Debian" to share their stories with us. Enjoy! Ana Guerrero Lopez (ana) Who are you? I'm a 30-something years old geek. I'm from Andalusia, Spain but live in France. What do you do in Debian? I work mostly on my packages, in sponsoring new people's packages and in this very blog you're reading now. I also maintain an unofficial Google+ page about Debian. At $PAID job, I work in an internal Debian distribution so from time to time, I get the opportunity to contribute back some of the stuff we do there. How and why did you start contributing to Debian? I started using Debian around 2003 switching from Mandrake. I was a happy Debian user when the Debian Women project started in the summer 2004. When I saw the project announced, I asked myself why I wasn't contributing to Debian and the rest is history... in a couple of weeks it'll be my 7 years DD-versary! If for some reason you want a longer reply to this question, read here. Beatrice Who are you? I am a PhD student with a degree in Biology. I am a computer fan since my first C64 and I am a self-taught computer geek wanna-be. And I am a bug fan - not software bugs, real bugs :) What do you do in Debian? I work on translations - doing the translation work itself, but also reviewing other translators' work and helping in coordinating the translation effort. How and why did you start contributing to Debian? I started using Linux because I liked the idea of an open source operative system based on collaboration and I began reviewing open source software translations. Since my first Linux system was Debian Potato and I sticked to Debian ever since, it only seemed natural to focus my translation work on Debian. Christine Caulfield Who are you? My name is Christine Caulfield. My day job is principal software engineer at Red Hat working on the cluster infrastructure components corosync & pacemaker. Outside computing I'm a musician and sound engineer. I play violin with lots of technology attached, and love avant garde music. What do you do in Debian? I'm not that active on Debian any more due to pressure of time, and maturity of the packages I work on. I currently maintain the, little-used, DECnet userspace packages and the, even less used I suspect, mopd bootloader. I used to maintain lvm2 for a while but dropped that a few years ago. How and why did you start contributing to Debian? My initial reasons for joining Debian were slightly selfish, to find a home for the DECnet project that I was heavily involved in at the time. I was a keep Debian user and people wanted a distribution where the software was easy to set up. DECnet is quite complicated for users to configure, being a totally independant networking stack to IP and so OS support is needed. Debian seemed like the logical place to make this happen. As mentioned above I got quite involved for a time and maintained other packages too. I picked up lvm2 because I was on the lvm2 dev team at work in Red Hat and as it was a new package at that time I seemed a logical choice. Elena Grandi (valhalla) Who are you? I'm a 30-something years old geek and Free Software enthusiast from Italy. What do you do in Debian? I'm currently maintaining a few packages (2 python modules and a python program) as a sponsored uploader; I'm also slowly looking around for other things to do (by preference technical, but not limited to packaging), with the aim to spend more time contributing to Debian. How and why did you start contributing to Debian? For a while I had being distro-hopping between "fun" distributions (the ones that break now and then) on the desktop while using Debian stable on the home server and in chroots. I was already doing marginal contributions to those distributions, where finding stuff that was missing was easy, but my perception as a stable user was that Debian was already working fine and probably didn't really need any help. Then I started to socialize on IRC with some DDs and DMs, and realized that my perception was superficial and that in reality there were dark holes in the depths of the archive where Evil festered and prospered and... ok, sorry, I got carried away :) Anyway, since I was actually using Debian more and more I decided to start contributing: I read documentation, I attended the useful IRC sessions on #debian-women and decided that it was probably best not to add new stuff, but look for things that I used and that needed help. Then nothing happened for a while, because finding stuff that doesn't work is hard (at least on my mostly textual systems). Then one day I was trying to write a python script that needed to verify gpg signed messages; it had to run on my Debian server, so I was trying to use python-pyme and its documentation was painful to use, while I remembered an earlier attempt using python-gnupg that was much more pythonic, but not available in Debian. In a fit of anger I decided to forgo all of my good intentions and actually add a new package: I checked the sources for problems, packaged, sent it to mentors@d-o, got reviews, fixed problems, resent and finally got sponsored and well, everything started. Francesca Ciceri (madamezou) Who are you? I'm Francesca, a 30-something Italian graduated in Social Sciences. What do you do in Debian? I'm a (non uploading) Debian Developer since 2011 and have been DPN editor, press officer, webmaster for www.debian.org and translator for the Italian l10n team. Recently, due to time constraints, I had to reduce my involvement and now only work on two things: writing/editing articles for bits.debian.org together with Ana Guerrero, and creating subtitles for the DebConf talks, in the DebConf Subs team. How and why did you start contributing to Debian? Basically thanks to the sudden abundance of free time - due to an health problem - and the desire to give something back to this wonderful operating system. After that, I found out that Debian is not only a great OS but also a very special community. Today, some of my dearest friends are people I met through Debian. :) Laura Arjona Who are you? I live in Madrid (Spain), and work as IT Assistant in the Technical University of Madrid (UPM). I'm married and I have a 4-years-old son. What do you do in Debian? In 2012 I started to clean spam and to translate Debian web pages into Spanish. I also follow the work of the web and publicity team, I hope I'll get more involved there too. And of course, I'm in Debian Women :) How and why did you start contributing to Debian? I'm using Debian at work since 2007 (servers), and in my desktops since 2010. I like very much that it is a community distro and I wanted to participate. I was already doing translations in other (small) free software projects, so I began here too. The Debian-Women list, the planet, and people in identi.ca helped me to learn a lot and feel part of the community even when I was not contributing yet. M nica Ram rez Arceda (monica) Who are you? My name is M nica Ram rez Arceda and I am an enthusiast of free software and sharing knowledge cultures: for me it's a kind of philosophy of life. I studied Maths a long time ago but ended up working as a developer for some years. Now I'm working as an IT teacher. What do you do in Debian? Debian is a huge project, so you can help in various scopes. Mainly, I work on packaging, fixing wnpp bug inconsistencies in BTS and helping in spam cleaning of the mailing lists. But I also enjoy doing some non-technical work from time to time: the project I am just now involved is organizing, with the rest of Debian Catalan community, a local team to propose Barcelona as the venue for a minidebconf where all the speakers will be women. How and why did you start contributing to Debian? In 2000 I discovered Free Software world and I fell deeply in love with its philosophy. Since then, I've been trying to do my best in different activities, like spreading the word, giving free courses, helping collectives and friends in technical stuff (from installing Debian to developing some helping apps for them)... but two years ago I was looking forward to join a free software project and I decided to try Debian, since it has been my first and only distro in my day-to-day life for about ten years. So, I wanted to give back Debian all what it had offered to me, but.... I thought I couldn't (hey, Debian is for real hackers, not for you little ant!), but I started to adopt some orphaned packages, do some QA uploads, fix some RC bugs, talk with some Debian Developers that helped me and encouraged me more than I expected, I traveled to my first Debconf... And one thing takes you to the other, and on March 2012 I became a DD. Now, I'm glad to see that everything that frightened me is not so scary :-)

As you know, I am not big on reviews, so you should disregard the remainder of this entry. I recently found myself in what is called a theatre complex , watching an adaptation of Moli re's Les Femmes savantes by Freyda Thomas, who is apparently famous for playing Alenis Grem on Deep Space Nine. Called The Learned Ladies, this translation to English manages to approximate some of the rhyme of the original, thereby making it unquestionably better than DS9. Also noteworthy is the all-female cast, cobbled together from two all-female theater groups. Elizabeth Neptune plays Chrysale, occasionally channeling the spirit of Jackie Gleason or bringing adorable ardor to such epic lines as Tea! I won't say anything about her eyes, but I will say something about her slippers. Sara Montgomery, as B lise, is delightfully crazy in her singing, dancing, costume changes, and other antics, which serve to transform this otherwise-completely-serious play into a comedy. I definitely won't say anything about her shoes. Madeleine Maby begins playing Philaminte well before the show starts. Spoiler alert: she sits on the stage, pretending to look through a telescope and make notes from before the house opens until right before the start of the first scene. I still feel exhausted by the thought of having to do that myself. L' pine is portrayed by Alyssa Lott, who also plays three minor roles. Her mastery of physical comedy is not wasted on this production. Marta Kuersten plays Clitandre opposite Sarah Brill's Henriette. While Marta's performance was quite good, she looks much better as a woman. I will not be saying this about everyone. Katie Honaker delivers visceral smarm and sleaze as Trissotin. Even her hairstyle is somehow evocative of contempt. Susan Finch plays Vadius and Le notaire. Susan was definitely most convincing as a man. Despite mutterings to the contrary, some suspension of disbelief was necessary for the other male roles, but not for Vadius, oh no. Finishing out the list we have Janna Emig as Martine, Francesca Day as Armande, and Kathryn Alexander as Ariste, with good performances, particularly in the second half. Even though it didn't have Coppertop from Strangers With Candy and a boy-band song-and-dance cover of To Be with You by Mr. Big, I recommend this play.

So, I've changed jobs, I now work for the incredibly awesome Mythic Beasts, So far it's been great, we've hit a few problems, we've made sane plans, and we're moving forwards and making things easier to manage long term. I've mostly been involved with debugging mac-mini boot problems, and getting them working with (as far as possible) stock kernels, rather than our previous set of custom compiled kernels, so that it's easier to upgrade later, and so that we're not having to maintain a whole set of patches that we shouldn't need to! We're also starting to package our own software that we use internally so that actually deploying new servers is becoming a lot easier, and configuration of our previous packages is now (mostly) handled by debconf, meaning that actually setting up backups is becoming much easier. We've also changed out main backup strategy from using a (slightly flaky) openvpn connection with loopback mounted ext3 filesystems to using rsync with the --fake-super option - the only thing that we've found slightly wrong with this so far is that --fake-super can't reconcile symlinks (it uses user level xattr to store the origional permissions, and with symlinks this doesn't work, because, apparently, symlinks should store user xattr attrbutes!). We also offer ipv6 for all our dedicated and vps customers, as per the mythic blog - and our 2 authoritative name servers are both v6 enabled. We're working towards making all of our core services available over both ipv4 and ipv6, and we should be there soon. It's fantastic to work for a company that has the technical knowledge and no-shit stance that Mythic Beasts has, we will hold our hands up if we do something wrong, and we'll tell you exactly what happened, why, and what we're doing to stop it from happening again. So, 1 month in, and I'm absolutely loving working for them, and I've been a customer of theirs since black cat networks sold their domain name side to them, and shortly afterwards bluelinux sold their virtual servers service to them. Our new VDS lite service is reasonably priced, and well spec'd. I thoroughly recommend our services, and obviously, we actually use our own vds service to provide some of our services - so it's as important to us that it keeps working as it is for our customers. Wow, so that was a very salesy post. Erm, next time, back to whinging about authors not having written the books I'm waiting for yet! :)

Recently, I've been attending a training course in Moldova about the representation of gender in the media and the influence on society of gender stereotypes.
The course was organized by Inesa Lupu, of Invento and financed by the UE as part of the Youth in Action program. It was the first time, for me, in this kind of international project and it was, in a word, fantastic.
Among the participants, there were people from Azerbaijan, Georgia, Italy, Latvia, Moldova and Slovenia.
That meant a great mix of cultures, languages and experiences.
And that was the key, in my opinion, of the success: coming from different countries and different social and cultural contexts meant that we were able to have a very broad and diverse point of view on the problem of gender stereotypes. So, here's some highlights on what we discussed. The media representation of gender (aka: gender issues are not only women issues) Tough Guise by Jackson Katz is a interesting documentary about the way the modern society - particularly in the US - defines masculinity as intrinsically tied to violence, aggressivity and "toughness" and on the consequences of this on the society as a whole. The author's theory is "that male violence, misogyny, and homophobia are inextricably linked to how we define manhood as a culture. The film gives special attention to how American media have glamorized increasingly regressive and violence masculine ideals in the face of mounting social and economic threats to traditional white male heterosexual authority". It then results clear that we cannot avoid to think about gender issues as women and men issues, because after all is the cultural definition of both femininity and masculinity that heavily influences the behaviour of men and women and their interaction.
In particular, I liked Katz's analysis of media's use of victim blaming speech while reporting of violences against women which tend to shift the focus from the violence perpetrated by men as part of definition of masculinity. Another documentary we watched, more focused on women representation, is MissRepresentation by Jennifer Siebel Newsom.
The film analyses the under representation of women in position of power, and the issue of women and leadership, especially in politics, in the US. Nothing too new, if you are interested in gender issues, as it is a widely discussed and studied topic, but still worth watching. After watching them, we formed little groups of three-four persons from different countries to discuss them, and it was even more interesting to listen the opinion of the guys (we had four male participants). Photography and Phototherapy As a workshop on media representation of gender, photography and advertisement were two of the main argument we spoke about. We focused on it for two days: our trainer, Lietta Granato - photographer and phototherapist - first gave us a lesson on photography, making us experimenting a bit with exposure times and diaphragm's aperture. Then she presented the evolution in the last 50 year or so, of the depiction of women in the ads.
And that, to be honest, was a bit upsetting.
I've already had seen one of the most important and widely known films on this theme, the Killing Us Softly series by Jean Kilbourne, but some of the ads Lietta showed to us were really really horrible. Actually, most of them were horrible. Commenting and deconstructing these ads would take a separate blogpost, probably, and there are many people more competent than me on the topic, so I've decided to simply share some of the worst ads in a collage, without much commenting. These are vintage, from the fifties to the seventies. Do you think we got better? Pff. They go from promoting violence and rape to heavily objectifying women. Special mention for the Compaq ad: as a geek woman I feel particularly insulted by the idea that I'm supposed to use a "pocket pc" as "pocket mirror". Because I wouldn't be able, obviously, to use it as a computer. Lietta also introduced us to photographic therapy and particularly the work of Jo Spence and Rosy Martin. If you browse Jo Spence's site, please be aware that there is a series of pics documenting all the stages of her illness (she died of breast cancer) and they are pretty intense. "In 1984, alongside Rosy Martin, Spence developed Photo-Therapy , adopting techniques from co-counselling. The considerable achievement of Photo-Therapy was to invert the traditional relationship between the photographer and the subject. If historically the subject had little control over their own representation, Photo-Therapy shifts this dynamic. The subject was able to act out personal narratives and claim agency for their own biography." (source: http://www.jospence.org/biography.html)
I love this concept and I really really love Spence's photos. To close on a happier note, I really suggest you to allocate 20 minutes of your time to watch this great talk by Nigerian novelist Chimamanda Ngozi Adichie, about the role of "single story" in shaping stereotypes and misunderstandings.

A person can find all sorts of implementations of backups using hardlink trees to save space for incrementals. Some of them are fairly rudimentary, using rsync --link-dest. Others, like BackupPC, are more sophisticated, doing file-level dedup to a storage pool indexed by a hash. While these are fairly space-efficient, they are really inefficient in other ways, because they create tons of directory entries. It would not be surprising to find millions of directory entries consumed very quickly. And while any given backup set can be deleted without impact on the others, the act of doing so can be very time-intensive, since often a full directory tree is populated with every day s backup. Much better is possible on modern filesystems. ZFS has been around for quite awhile now, and is stable on Solaris, FreeBSD and derivatives, and Linux. btrfs is also being used for real workloads and is considered stable on Linux. Both have cheap copy-on-write snapshot operations that would work well with a simple rsync --inplace to achieve the same effect ad hardlink farms, but without all the performance penalties. When creating and destroying snapshots is a virtually instantaneous operation, and the snapshots work at a file block level instead of an entire file level, and preserve changing permissions and such as well (which rsync --link-dest can have issues with), why are we not using it more? BackupPC has a very nice scheduler, a helpful web interface, and a backend that doesn t have a mode to take advantage of these more modern filesystems. The only tool I see like this is dirvish, which someone made patches for btrfs snapshots three years ago that never, as far as I can tell, got integrated. A lot of folks are rolling a homegrown solution involving rsync and snapshots. Some are using zfs send / btrfs send, but those mechanisms require the same kind of FS on the machine being backed up as on the destination, and do not permit excluding files from the backup set. Is this an area that needs work, or am I overlooking something? Incidentally, hats off to liw s obnam. It doesn t exactly do this, but sort of implements its own filesystem with CoW semantics.

I ve transitioned to a new key announcement here or below. If you ve signed my key in the past please consider signing my new key to get it integrated into the web of trust. Thanks!

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1,SHA256
Sun, 2013-10-13
Time for me to migrate to a new key (shockingly late - sorry!).
My old key is set to expire early next year. Please use my new key effective
immediately. If you have signed my old key then please sign my key - this
message is signed by both keys (and the new key is signed by my old key).
old key:
pub 1024D/FBD3EB8E 2002-07-20
Key fingerprint = 9222 8732 859D 25CC 2560 B617 867B F9A9 FBD3 EB8E
new key:
pub 4096R/AAC0E286 2013-10-13
Key fingerprint = 8244 0CEA B440 83C7 9431 D2CC 298E 9A19 AAC0 E286
The new key is up on the keyservers, so you can just pull it from there.
- -Rob
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2.0.19 (GNU/Linux)
iEYEARECAAYFAlJZ8FEACgkQhnv5qfvT644WxACfWBoKdVW+YDrMR1H9IY6iJUk8
ZC8AoIMRc55CTXsyn3S7GWCfOR1QONVhiQEcBAEBCAAGBQJSWfBRAAoJEInv1Yjp
ddbfbvgIAKDsvPLQil/94l7A3Y4h4CME95qVT+m9C+/mR642u8gERJ1NhpqGzR8z
fNo8X3TChWyFOaH/rYV+bOyaytC95k13omjR9HmLJPi/l4lnDiy/vopMuJaDrqF4
4IS7DTQsb8dAkCVMb7vgSaAbh+tGmnHphLNnuJngJ2McOs6gCrg3Rb89DzVywFtC
Hu9t6Sv9b0UAgfc66ftqpK71FSo9bLQ4vGrDPsAhJpXb83kOQHLXuwUuWs9vtJ62
Mikb0kzAjlQYPwNx6UNpQaILZ1MYLa3JXjataAsTqcKtbxcyKgLQOrZy55ZYoZO5
+qdZ1+wiD3+usr/GFDUX9KiM/f6N+Xo=
=EVi2
-----END PGP SIGNATURE-----

Back in February, I wanted a new laptop for my work, so I bought a fancy Dell Latitude E6540 laptop. Bad luck, it was giving my sore eyes and horrible headaches, to the point I couldn't work more than a dozen minutes with it. As in my work, we were not allowed to buy PC laptops with any other vendor, my boss convinced me to get a 15'' macbook pro retina (yes that's about as expensive a laptop as you can get). Although quite reluctant at first, I did need a new laptop, so I gave in. Of course, I had to install debian on it. I booted once or twice on macos to leave enough space for Debian and install rEFIt so that I could boot into it. I had to use version 3.9 of linux else it wouldn't boot.After about 8 month, I must say I'm quite pleased with the beast. The retina display is very neat (a 2880x1800 resolution!), and it is pretty fast. There are two annoyances though:

• I never managed to get either the non-free NVIDIA drivers or the integrated intel graphics to work. The NVIDIA driver give blank screen on X startup, while it doesn't even start with the intel drivers (and I've tried all the tricks I could find around). The fine point is that I don't have any hardware 3D acceleration !
• The wireless network is pretty unstable.

Another point is the update of GRUB: Debian's post-install scripts don't play nice with the EFI setup, so here is what I have to do to update to a newer version of grub, (and it's also what I had to do initially to install GRUB):

# mount /dev/sda1 /mnt
# grub-install --efi-directory=/mnt

The /dev/sda1 partition is the so-called EFI partition. I think it is created by rEFIt and it is essentially empty.