i've been doing burn-in on a new server i had hoped to deploy months
ago and can't seem to figure out the cause of data corruption i've
been seeing. the SAS controller is an LSI SAS3801E connected to an
xTore XJ-SA12-316 SAS enclosures (vitesses expanders) full of seagate
7200.10 750-GB SATA drives.
the corruption is occurring in ext3 filesystems that live on top of
an lvm2 RAID 0 stripe composed of 16 2-drive md RAID 1 sets. the
corruption has been detected both by MySQL noticing bad checksums and
also by using md's "check" (sync_action) for RAID 1 consistency.
most recently we got two cases of the storage stack apparently
writing a mysql 16K page starting at the wrong 512-byte (sector)
boundary. in both cases it was at too low a sector. one page was 13
sectors too early, the other 34 too early. in both cases, one disk
in each mirror set had the correct data and the other incorrect
(apparently ruling out everything above md). unfortunately, the
problem is not easily repeatable. the system can run for days with
terabytes of writes before we notice any corruption.
we're running RHEL 5.1's kernel and drivers and i understand that
these lists are for vanilla kernel support. i've already engaged
redhat support, but i just wanted to see if anybody else has seen
something similar or anybody has any brilliant troubleshooting
ideas. swapping drives, enclosures, HBA's, cables, and sacrifices of
animals to gods have so far not been able to make the world right.
tia,
marc
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