John McMonagle wrote:

Have a raid1  backup server that seems to get corrupted.
This is the 3rd time in about a year.
Have 2 other backup servers that were cloned from this one that have 
no problems.

Done a couple kernel upgrades recently.
Now has 2.6.18-2 kernel.
It's based on Debian sarge.

It's a low end Intel server motherboard using ata_piix sata driver.
Have another mother board just like doing raid1 with sata drives that 
has had no problems but it has a much lighter disk load.
smartctl has never shown any problems.
In /sys/block/md2 did
echo check > syncaction
No error messages but mismatch_cnt  is 1152.
rc0/errors and rc1/errors are both 0.

I'm guessing a hardware problem.
Any suggestions? 

Since memory is the easiest to test, I'd try memtest86+ for at least 12 
hr. If this were PATA I'd suggest replugging the cables, but it's lower 
probability with SATA. Still, probably worth trying.

-- 
bill davidsen [off-list ref]
  CTO TMR Associates, Inc
  Doing interesting things with small computers since 1979