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git merge 2013

11 May 2013 (by Jan-Erik)

Friday and Saturday I attended gitmerge, a free Git user conference in Berlin.

Friday was filled with lots of lightning talks with lots of interesting ideas, projects and stories. I tried to collect most of the projects or slides in a link list on pinboard. More info about each project can be found in the git repo from the userday.

Saturday was planned as hackday. @mislav wanted to improve hub, a wrapper for git. He listed the planned features in ticket #1. I tried to help with that, but most mentioned issues were a little over my head without ever have looked at the source. After a lot of code reading I could atleast fix a little bug and comment on another issue.

To wrap things up, git merge was a nice little conference, showing off interesting projects and ideas and I had a few little talks with nice people.

(Oh, and of course visiting Berlin is always nice)

irregular backups with rsnapshot (and rsnapshot_ii)

22 Jan 2013 (by Jan-Erik)

As stated in the last post I bought a big 2TB HDD for backups. My only computer right now is a Laptop so regular backups are not possible (due to not having the hdd with me all the time)

I needed another way for easy full and incremental backups without relying to much on specific intervals.

I came across rsnapshot, which - well - does depend on regular intervals. But here comes rsnapshot_ii, a small wrapper script for rsnapshot.

It “fixes” these two problems the author (and I) had:

Backups with irregular intervals.
Missed backups.

I uploaded my config here (gist):

And as promised in the last post the script I use to mount the HDD: mount-backup

Problems after disconnecting LUKS device

14 Jan 2013 (by Jan-Erik)

Yesterday I got my 2TB backup disk. I formatted it and then used LUKS to encrypt it and LVM for the Volume Management. After I copied some files to the new disk, I unmounted the disk, unplugged it and …

… Oh, shit.

I forgot to cryptsetup luksClose it.

That’s not a good thing to do. Always remember to luksClose! It’s so much easier

So after reconnecting the device, you can’t really decrypt and mount it, because it did not get unmapped (/dev/mapper/name still exists and so do /dev/name/*)

No problem, we fix that!

(in the following my mapping name is extern, change accordingly)

First see current status, especially Open count

dmsetup info

Now remove each mapped device (-backup and -media for me, I have 2 partiions on the disk):

dmsetup remove extern-backup
dmsetup remove extern-media

Once again check Open count, it should be 0 now. If so, go on and remove the mapping:

dmsetup remove extern

Now you got rid of all old mappings. Let’s try to mount the disk again. Plug it in, then do:

cryptsetup luksOpen /dev/sdb2 extern

Type your password. If the Volume Groups are missing, use:

vgscan
vgchange -ay extern

Now you can mount your partitions:

mount /dev/extern/backup /mnt/backup

Once you’re done, deactivate the volume groups and close the crypt device:

vgchange -an extern
cryptsetup luksClose extern

Now remember to always use these two commands after unmounting the device and use the following to open it:

vgchange -ay extern
cryptsetup luksOpen /dev/sdb2 extern

I wrote a little helper script which does exactly these steps as needed. I’ll include it in my next post, when I talk about how I use the setup for backups.