[ale] Seagate 1.5TB drives, bad blocks, md raid, lvm, and hard lock-ups

[deritchie at gmail.com (David Ritchie)]

You might want to read the steps found at http://blog.herbertm.ca/46 prior to
setting up the RAID via mdadm - evidently there are differences
between vendors and drive lines
regarding when drive reallocation occurs. I would probably start off by

   dd if=/dev/zero of=/dev/sde bs=1024K

(assuming /dev/sde is your drive of interest) to force a write of all
zeros to the mechanism,
and then dd if=/dev/sde of=/dev/null bs=1024k to see that you can read
all the sectors.

You really shouldn't have to be doing any of this - but it sounds like
Seagate is having some teething problems
with the new mechanisms.

  BTW, this technology was known as Automatic Reallocation on Read Error
(ARRE) or Automatic Reallocation on Write Error(ARWE) , and was
typicallly a Mode Select command to
the drive in the days of SCSI controllers... ATA drives do it a bit
differently, but the same concepts apply.
The way it works is that there are a certain # of reserved tracks, and
if the ECC fails on a particular sector,
either the track is rewritten and bad area ends in a unmapped sector,
or the whole track is moved to
a spare track (which can result in a performance hit in some cases
while this operation completes).