[linux-lvm] File Corruption on LVM LV's in same VG

[Andreas Dilger]

On Feb 05, 2002  13:11 -0500, Erik Zweers wrote:
> The system was repaired and believed to be running properly, until
> yesterday where we discovered that some of our ISO's were wrong,
> consistently wrong in inconsistent locations.  I've pasted in a record
> of the symptoms.  If anyone has any advice on what else to diagnose (if
> your intrested in what is wrong) or how to repair It would be greatly
> appreciated.

I would suspect RAM or IDE problems.  If LVM is broken, it will stay
broken, and if it is working it will stay working in the absence of
other problems.  The failure symptoms would not look like this.

> I have not rebooted the machine yet, wanting to be sure that any
> diagnoses that can be done is done.

Any output in dmesg?

> [root at ike iso]# cmp -l enigma-i386-disc1.iso ~carl/enigma-i386-disc1.iso
> 2549832  77  67
> 13431928 177 167
> 14489440 376 366
> 27451404 177 173
> 33149724 376 336
> 86298228 177 167
> 116907524 372 332
> 119130964  77  67
> 121124171 376 356
> 
> 
> [root at ike iso]# cmp -l enigma-i386-disc1.iso ~carl/enigma-i386-disc1.iso
> 2549832  77  67
> 11455071 177 167
> 13431928 177 167
> 18043044 277 273
> 24780964 277 273
> 86298228 177 167
> 94133044 370 330
> 106966431 177 167

Looks exclusively like single-bit errors.  Either RAM or IDE cable/driver.
If it was RAM you would also have oopses or errors elsewhere.  Try turning
off UDMA on the drive, update the IDE driver, new cable, etc.

> | wc -l     62
> [root at ike iso]# ls -l enigma-i386-disc1.iso
> -rw-r--r--    1 root     root     677961728 Feb  4 20:31
> enigma-i386-disc1.iso
> 
> [root at ike iso]# fsck -n /dev/ide/iso
> Parallelizing fsck version 1.23 (15-Aug-2001)
> e2fsck 1.23, 15-Aug-2001 for EXT2 FS 0.5b, 95/08/09
> Warning!  /dev/ide/iso is mounted.
> /dev/ide/iso: clean, 24/1281696 files, 1351397/2560000 blocks

Given that you only have single-bit error rates in the order of 1/10^7,
the chance of such an error happening in the ext2 metadata is unlikely.

Cheers, Andreas
--
Andreas Dilger
http://sourceforge.net/projects/ext2resize/
http://www-mddsp.enel.ucalgary.ca/People/adilger/