December 14, 2008

I need to back up data more often

Friday night my desktop linux machine crashed. That is pretty unusual: it usually runs 24x7 for months at a time. I have had one or two crashes recently due to the video drivers (I guess) because basically the video goes out, but I can still ssh in from another machine and the desktop is still alive. I've been running Fedora 8 for a long time on it, and haven't been able to get updates lately due to some broken packages and wonky yum state I got the machine into. I haven't really had time to try to fix it, and just figured that I would upgrade to Fedora 10 when that came out.

Well, Fedora 10 came out, and my machine was giving me problems, so I thought I would do an upgrade. I downloaded the DVD, threw it in and started the process.

The install went fine, but there were problems with the video card drivers. I had been using the binary drivers from AMD for my Radeon HD2400 (card of some sort) and they worked well for playing video. I never could get video to work with compiz, so I didn't have pretty whiz-bang effects, but that was fine because I could watch videos on the machine, which is basically what it is for.

The problem was that I couldn't get the HD2400 card to display the screen right. I read up on stuff, and it turns out that the newest version of the drivers hasn't been updated for Fedora 10 and lots of people are having problems with those drivers now. Great. Well, I can always fall back to the onboard Intel G31 (I think?) video card. Unfortunately, that gave me a different just as fatal problem: there are some strange messages in the log about the X server going into some sort of infinite loop. It basically locks the screen. I couldn't manage to get that working either.

So I am now in a state with that machine where I can't boot it graphically. It will run fine in text mode. That isn't very useful for watching videos. Things were working great with Fedora 8, but I had borked the install a bit, and now it is out of support anyway. So I am now planning to move back to Fedora 9, but I can't downgrade without wiping all the data on the hard disk. This is a problem because I've got a LVM install binding two 500gig drives together, and they are not backed up. About 800gig is video and user data that I want to keep. Another 100gig of system data that I don't care too much about. But no backups.

Well, I have a 500gig external drive, and just bought another 500gig external, and in single user mode I am now backing up the machine. It looks like it will take about 24 hours to do a backup using the tar copy trick (I can at least see what files are being copied that way: "tar cf - . | (cd /mnt/backup/data && tar xBfv -)")

It is super slow. I would like to use dd or something, but because I'm using LVM the sizes don't work out so that I can mirror the partitions. I don't know the intricacies of dd anyway. At least I'll get a backup of all my data now (one of the drives I had was firewire, the new one is only USB. The firewire drive was a lot quicker.) Also when I re-install Fedora 9 (because driver support still isn't there for 10) I will do a smarter partitioning: put /home and /data on their own mount points in the LVM so that future installs can blow the other stuff away and leave that data intact.

Actually, I'm still not clear on the best use of LVM. Should I make a second LVM LogVolume group just for /home and /data? That sounds like it would be safer to me, because then I could make multiple LogVolume groups for different installs if I wanted to, and blow away the whole thing on an upgrade. But LVM is still a somewhat confusing concept for me. I understand what it is doing, I do not understand practically what are the best ways to set things up to keep your data safe. I had a different problem with LVMs once where the LVM itself went corrupt, and basically I just had to kiss that machine goodbye.

I think I can use my standard rsync trick for backups from here on out, but Apple makes this so much easier with Time Machine.


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