nip3o's questions

I have are large-ish database which consists of 100+ tables. A few of these tables are so big that running VACUUM on them takes a couple of hours, so I don't want to run it on these tables. Is there any way to run VACUUM with a dynamic list of tables, i.e. something like below?

VACUUM (SELECT table_name FROM information_schema.tables WHERE table_name not in ['list', 'of', 'big', 'tables'])

It would of course be possible to just list all the table names manually, but ideally I would like to have a way to do it dynamically.

As far as I know, LVM makes it possible to take snapshots of a volume. There are also a number of file systems (ZFS, Btrfs, reiserfs, ...) which supports snapshots.

However, I've never understood the difference between LVM snapshots and file system snapshots. If it's possible to take snapshots with LVM, why does someone take their time to implement it in a file system?

Edit: Is any of them preferred in some situations? Why?

I've got a server running Debian Squeeze and a 3x 500 GB-drive RAID5 system which I haven't set up myself. When booting, the status of one partition in the RAID-array seems to be bad.

md: bind<sda2>
md: bind<sdc2>
md: bind<sdb2>
md: kicking non-fresh sda2 from array!
md: unbind<sda2>
md: export_rdev(sda2)
raid5: device sdb2 operational as raid disk 1
raid5: device sdc2 operational as raid disk 2
raid5: allocated 3179kB for md1
1: w=1 pa=0 pr=3 m=1 a=2 r=3 op1=0 op2=0
2: w=2 pa=0 pr=3 m=1 a=2 r=3 op1=0 op2=0
raid5: raid level 5 set md1 active with 2 out of 3 devices, algorithm 2
RAID5 conf printout:
 --- rd:3 wd:2
 disk 1, o:1, dev:sdb2
 disk 2, o:1, dev:sdc2
md1: detected capacity change from 0 to 980206485504
 md1: unknown partition table

mdstat also tells me the partition is missing:

Personalities : [raid1] [raid6] [raid5] [raid4] 
md1 : active raid5 sdb2[1] sdc2[2]
      957232896 blocks level 5, 64k chunk, algorithm 2 [3/2] [_UU]

md0 : active raid1 sda1[0] sdc1[2](S) sdb1[1]
      9767424 blocks [2/2] [UU]

When running sudo mdadm -D, the partition shows up as removed, and the array as degraded.

/dev/md1:
        Version : 0.90
  Creation Time : Mon Jun 30 00:09:01 2008
     Raid Level : raid5
     Array Size : 957232896 (912.89 GiB 980.21 GB)
  Used Dev Size : 478616448 (456.44 GiB 490.10 GB)
   Raid Devices : 3
  Total Devices : 2
Preferred Minor : 1
    Persistence : Superblock is persistent

    Update Time : Thu Aug 11 16:58:50 2011
          State : clean, degraded
 Active Devices : 2
Working Devices : 2
 Failed Devices : 0
  Spare Devices : 0

         Layout : left-symmetric
     Chunk Size : 64K

           UUID : 03205c1c:cef34d5c:5f1c2cc0:8830ac2b
         Events : 0.275646

    Number   Major   Minor   RaidDevice State
       0       0        0        0      removed
       1       8       18        1      active sync   /dev/sdb2
       2       8       34        2      active sync   /dev/sdc2

/dev/md0:
        Version : 0.90
  Creation Time : Mon Jun 30 00:08:50 2008
     Raid Level : raid1
     Array Size : 9767424 (9.31 GiB 10.00 GB)
  Used Dev Size : 9767424 (9.31 GiB 10.00 GB)
   Raid Devices : 2
  Total Devices : 3
Preferred Minor : 0
    Persistence : Superblock is persistent

    Update Time : Thu Aug 11 17:21:20 2011
          State : active
 Active Devices : 2
Working Devices : 3
 Failed Devices : 0
  Spare Devices : 1

           UUID : f824746f:143df641:374de2f8:2f9d2e62
         Events : 0.93

    Number   Major   Minor   RaidDevice State
       0       8        1        0      active sync   /dev/sda1
       1       8       17        1      active sync   /dev/sdb1

       2       8       33        -      spare   /dev/sdc1

However, md0 seems to be ok. So, what does all this tell me? Can the disk be faulty even though md0 is working? If not, can I just re-add /dev/sda2 to the md1 array to solve the problem?

I've got an old computer running Ubuntu Server 10.04, which acts as router, file server and web server. A couple of weeks ago I inserted a PCIe video card, since the motherboard did not have any video outputs. Since then, I now occasionally get IO and bus errors. When this happens, most binaries such as sudo, vim, or cat, typically results in the error message I/O error. Listing most directories works, but ls / gives Bus error. Everything starts to work again if I perform a hard reset of the computer.

The disk, which is less than a half year old, is not a part of any RAID system. The server is not heavy loaded and has a Core 2 Duo CPU and 4 GB RAM.

I suspect that this may be a hardware issue. However, is there any way to know which hardware to suspect? The hard drive, the motherboard, or something else?