How
pivot_root won against a stupid RAID controller
This post is brought to you by a very stupid 3ware 9650SE RAID
controller, which doesn't understand the concept of growing a RAID
array after all disks have been replaced by bigger ones. Or, well, it
can, but the procedure, involving sending array dumps to the technical
support, then receiving a program to run under DOS (!), doesn't
inspire me with confidence. Furthermore, this stupid RAID card doesn't
allow easy reordering (if it's possible, and I just missed it, please
let me know) of the RAID arrays at runtime, only from the BIOS screen,
and I didn't have access to that (only poor man's serial console under
Linux).
So, after buying new
harddrives, and replacing the
original ones in the RAID1 array with double the capacity, I realised
I have to do a manual conversion. Basically, go into single-user mode,
remount all read-only, split the RAID1 array into its (identical)
components, change root directory to the second disk, re-partition the
first disk, copy the data from the 2nd to the 1st disk, then re-add
the 2nd disk to the 1st one (repartitioned) to re-establish the RAID1.
All this, on a headless (no keyboard, no VGA) machine, just with a
serial console. Of course, if this is just your local machine, you can
easily reboot from an external media, and do all this easily from a
full user-space. In any case, I'm writing this down, as there seem
to be no easily findable guides on how to do the resize on a 3ware
with its restrictions.
Procedure
Disclaimer: you might lose data via this, there are no
guarantees. Have up-to-date backups.
First, make sure you have power control (you can power-cycle the box
if needed) and the serial console works.
Also, make absolutely sure that the RAID array is fully
consistent, and that you don't have any bad sectors on the drives, as
you will lose redundancy during the operation.
If
/usr is not on your root file-system, then you need to copy
/usr/sbin/chroot to somewhere on it. Also, if you have tools for the
array that are not on your root file-system, you should copy them
there now. In my case, that was
tw_cli.
First reboot
Reboot into
init=/bin/sh.
Note: I've tried to simply go into single-user mode, or to reboot with
emergency, but this doesn't work, because in both modes, beside the
init process with PID 1 and your shell, there's another
init
process (the parent of the shell), and I didn't know how to tell it to
re-execute itself. To the main
init process it's easy, you just run
telinit u, but that child keeps the old root directory mounted. If
it's possible to re-exec that child too, then this step can be
skipped please let me know how!
Changing the root mount
Make sure everything is mounted read-only (should be), then split the
raid array into its component drives, using whatever tool the card
needs. For me, it was:
# tw_cli /c0/u0 migrate type=single
The second drive now should be visible e.g. as
/dev/sdc, so mount it
somewhere, and
pivot_root to it:
# mount -o ro /dev/sdcX /mnt
# cd /mnt/
# pivot_root . mnt/
# exec chroot .
At this point, the new root (on some partition on
/dev/sdc) is mount
at the root, and the
exec call replaced the current shell with
another one that has the right root directory.
So nothing should keep the old root directory (at
/dev/sdaX) in use,
and
umount /mnt (or
umount /dev/sdaX) should succeed now.
Recreate the first raid array
Now, since it's no longer in use, you can delete and recreate the
first raid array.
Once it's available, you have two choices:
- either do a bit-for-bit copy, using dd, from
/dev/sdc to
/dev/sda, then run sfdisk -R /dev/sda to re-read the changed
partition table on the target drive
- or repartition
/dev/sda if you also want to change the partition
layout
I did the latter, since I wanted to use the new alignment standards
(the initial installation was still using sector 63 for the boot
partition, etc.) as a future preparation for either SSD or 4K-sector
drives. So I used:
fdisk -cu /dev/sda, and created partitions accordingly- then re-did my physical volume for LVM, but with
--dataalignment
1024k, to have the same megabyte alignment (yes, I went a little
overboard)
In any case, either copy the entire disk, or each partition in turn,
or possibly
pvmove from the old to the new disk, etc.
Switch back the root mount
At this point,
/dev/sdc is no longer used, and you can again change
the root directory. This is similar to the first
pivot_root, but now
using
/dev/sda as a target. All the instructions are the same.
Convert back to RAID1
Now, since (in our example)
/dev/sdc is no longer in-use, you can
delete that drive and rejoin it to the first drive, recreating the
RAID1 array. In my case:
# tw_cli
/> /c0/u2 delete
blah blah [y/n] y
/> /c0/u0 migrate type=raid1 disk=X
At this point, the machine is again redundant (or will be once the
resync finishes), but it still needs one more step or it won't boot
correctly.
Reinstall the boot-loader
Now, for reinstall the boot loader, you'll probably need to mount
/boot (and mount it read-write), and do whatever you need. In my
case, I re-ran
lilo, but
grub-install /dev/sda should also work.
Final reboot
And now, you only need to reboot into the normal, resized
system. Since you can't easily use
shutdown when booted with
/bin/sh as init, just use
/proc/sysrq-trigger to
sync/unmount/reboot.
Thoughts
While I use a hardware RAID controller for the battery backup it
offers, I have never thought it cannot do such a simple operation
(compare with
mdadm --grow /dev/mdX --size=max).
Second, I knew about
pivot_root but have not used it before. It's a
very very nice thing, and the only downside is that you can't really
use it with more than a few processes, since it's hard/impossible to
change a random process' root directory. But anyway, it works, and
it's damn handy for doing things to the root file-system or in general
to the root drive (e.g. just repartitioning it) when you can't boot
from another media (e.g. remote machine).
Roland Mas writes an interesting article about decentralized naming, in which he says: 
Steve Jobs is a name that comes up a lot when talking to businesspeople, especially in the technology industry. His ideas, his background, his companies, their products, and his personal style are intertwined in the folklore of tech. I have no idea whether most of it is fiction or not, and I write this with apologies to Mr. Jobs for using him as shorthand. I have never met him, and my point here has nothing to do with him personally.
What I want to discuss is the behavior of people who invoke the myth of Steve Jobs. In my (entirely subjective) experience, it seems to me that there is a pattern which comes up again and again: People seem to want to discuss and emulate the worst of his alleged qualities.
Jobs 
For some time, I've had this idea brewing for how the 'net would work
without DNS. Initially I was mostly thinking of how to get rid of the
dark side of the registrar business, but it appears that maybe it
could help with security in general too. It may not be feasible at
all, or I may have forgotten extremely crucial points. I'm not a DNS
guru, so bear with me and consider this as a thought experiment. This
is, however, a proposal for how the Internet could be made truly
decentralized, or acentric. Made so, because it currently is very
centralized on at least two counts: the DNS is an inherently
hierarchical structure of authority; and so is the situation with the
SSL certificates used for securing websites. Let's start with DNS,
if you will.
Basically, the idea is to replace the current Domain Name System,
which is centralised in nature (even if subdomains can be delegated)
with a fully decentralised system with no central authority.
The point of current DNS is to map names to IP addresses in a unique
way. It currently works by registering a this name is managed by
such-and-such server, ask for details at such-and-such IP address
message. Of course, since there's only one namespace (or a limited
number thereof, if you consider that TLDs are different namespaces),
there needs to be a central authority to resolve conflicts, because
some names will be more popular than others.
I propose to start with a cryptographic key pair (think GPG key).
Anyone can create their key pair; we assume that it's extremely
unlikely for two people to generate the same keys, and that it's also
very hard for two people to generate keys with the same fingerprint.
By (being the only one) knowing the secret part of a key, I am the
authority on what can be signed with it. I could for instance sign
records that say that 
In my 
* No, we don t have 
Usually I like to monitor as much as possible. but unfortunately my cable provider does not allow to access the cable modem via SNMP, so I had to find a different way to retrieve at least some basic information. After a bit of googling I figured out how to access the web interface of the Scientific Atlanta modems. The model here is a EPC2203 - seems to work for various models, though.
These modems do not only provide access to the traffic within the cable network on their internal networking port (ever tried tcpdump on that?), but they also have their own IP (192.168.100.1). To be able to access the modem you should add something like
This morning, my laptop was stolen from my parked car while I was jogging. I do not want to make a big deal out of it.
Still, even though I am sure it was not targetted at my data (three other people at least were reporting similar facts in the same area), and the laptop's disk will probably just be reformatted, I am trying to limit the possible impact of my cryptographic identification being in somebody else's hands.
GPG makes it easy: I had on that machine just my old 1024D key, so it is just matter of generating a revocation certificate. I have done that, and uploaded it to the SKS keyservers - Anyway, here is my revocation certificate:
From the 17th to the 19th of September in Perugia, Italy, it took place the 5th edition of the Italian Debian Community Conference, which has been attended by many contributors and users.
For the first time, the event has been organized in collaboration with the Italian Ubuntu community, as to create a new joint conference in order to foster shared contributions and emphasizing the large common ground of our projects. This new experimental kind of mini-conference was then labeled DUCC-IT, to reflect both the local profile and the mutual collaboration.
After the initial social night, spent discussing of several ongoing free software efforts and having dinner all together, the conference official opening started on Saturday, temporarily housed at University of Perugia, with a series of talks and hands-on session aimed at recruiting new contributors to work on development, translations, documentation writing and marketing. It has been a good opportunity to celebrate the 
There are corners of the Internest where foolish people congregate, and invent stories. These foolish stories are then read as gospel by trusting people, and reposted, until the original made-up source is concealed from view. As an attempt to stem this flow of disinformation, here are some commonly held but incorrect beliefs about the Mono framework, and an explanation of the reality of the situation, as far as I understand it.
The next Mono version is co-developed with Microsoft
There is a grain of truth behind this one, but it s a gross mischaracterisation. Mono 2.8, when it ships, will bundle, for convenience, a number of Free Software libraries, which are released by Microsoft under a license considered Free Software by the Free Software Foundation, the Ms-PL. These are:
I'm a fan of LC_MESSAGES=de_DE and localized web pages -- almost.
Unfortunately, the wording of many translations in Debian often drives me nuts.
This applies mostly to web pages and package descriptions. Apologies to all
hard-working translators -- the percentage of good translations does not
outweigh the "wtf" cases for me. Still, I didn't want to switch to English for
all the web.
Rhonda pointed me to a Firefox ^W Iceweasel plugin:
[Nothing related to Debian here, move on if you don't care about my recurring obsession with the end of the world, 
Peter Cox on model complexity