[linux-lvm] LVM seems to be causing SCSI errors.

["Karl" <rmvzj001@sneakemail.com>]

This is a real odd problem and my searching of the mailing lists and
docs has not shed any light on it.

I created 3 logical volumes (with lvm 1.0.1r2, r3 and r4) across 4 disks
on a dual 300 MHz PII running 2.4.6 (same behavior under 2.4.9) and
readhat 7.1. After this I noticed IO errors while reading some files
and SCSI errors when accessing lvol2. The errors were similar to the
following


Sep 28 17:11:21 gar kernel: scsi0: ERROR on channel 0, id 11, lun 0, CDB: Read (10) 00 00 ba e1 97 00 00 80 00 
Sep 28 17:11:21 gar kernel: Info fld=0xbae1e6, Current sd08:21: sense key Medium Error
Sep 28 17:11:21 gar kernel: Additional sense indicates Unrecovered read error
Sep 28 17:11:21 gar kernel:  I/O error: dev 08:21, sector 12247456


lvol2 spanned two disks and all the errors were on only one of them. I
naturally thought that the problem was a hardware problem with the
disk. The only odd thing was that lvol1 which spanned the same two disks
did not have any errors.

The first thing I tried was an mke2fs with bad block checking on
lvol2. It found several errors and when I copied the files back on new
errors cropped up and more files were lost.

The next thing I did was to move all the data off of that disk (pvmove)
and then did a low level format on that disk. No errors were detected
during the low lever format nor the verify I did after that. I then did
a mke2fs with bad block checking on the disk without LVM. No errors. I
then did a pvcreate and re-created lvol2 and then did a mke2fs with bad
block checking. Once again the SCSI errors. Removing that drive from LVM
and formatting yet again without LVM showed no errors.

Moving lvol2 to a different physical volume results in the SCSI errors
moving to that volume.

I am now convinced that the problem is with LVM and not with the
hardware. I still have two other logical volumes (lvol1 and lvol3) that
are not having ANY problems at all. Does anyone have any suggestion on
how to solve this one?

Thanks.


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