[linux-lvm] Random file system errors

["Gaute Lund" <gaute@idrift.no>]

I have searched the web and the mailing list without finding anything
similar to this.

At home I have an LVM setup. Reading data gives random errors. I only
recently discovered it's an LVM issue. I think.

The issue: If I md5sum largeish files, or test archives, I sometimes get
errors or randomly different md5sums. Like now, I have 11 folders, all with
rar files in parts: some 300 15MB pieces in 6 folders/sets, totaling 4,2GB,
and 560 50MB pieces in 5 folders/sets, totaling 23G.

OK, so I "rar t" all of these 5 times over. Errors pop up randomly, 52 times
in the 50MB pieces, 10 times in the 15MB pieces. That's about 1 error for
every 2,1GB of data read. Md5suming multiple files gives about the same
error rate.

If I run repeated test on a rar set small enough to fit in cache mem, I get
errors, but they are indentical with each run. 

Is it really an lvm problem? Well, I have created new LVs and use different
filesystems, ext3, xfs, jfs - they're all the same. If I create an md on
some other disks, and put a filesystem on it, without LVM, no problems.

I can't find any other errors, in any logs or dmesg. The errors weren't
there to begin with, they came at one point and got worse. It took a while
before I realized it was a generic disk problem, and for a period I kind of
gave up on it. So it's been there for ... maybe six months?

The VG consist of two software RAID 5 md's, one consisting of four 200GB
IDEs, one of five 500GB SATAs, yielding av VG totaling 2,37TB. Other
hardware is 4GB memory and a Core 2 Duo 6600 CPU.

Machine runs Ubuntu 8.10 with kernel 2.6.27-11, and
  LVM version:     2.02.39 (2008-06-27)
  Library version: 1.02.27 (2008-06-25)
  Driver version:  4.14.0

But the VG was originally created long ago, on LVM1 even.

Well, I guess that's it. Any other information that could be helpful? Any
way I could debug this?

Best regards
Gaute Lund