Re: [tlug] Setting up a RAID 1 with Ubuntu (Was: Hard Drive Failure)

[Francois Cartegnie <fcartegnie@example.com>]

Le mardi 16 septembre 2008, Curt Sampson a écrit :
> Generally software RAID doesn't. So long as you've got two chunks of
> blocks available that are the same length, on two different devices, you
> can do a RAID 1 across them.

Blocks of the same lenght, and the same number of plates / similar geometry.

More than any firmare differences, recent SATA drives now comes with NCQ (and 
probably that each manufacturer has it's own implementation). So using drives 
from different brands can't guarantee that your reads and writes will be done 
the same way on the drives.
Alternative is by setting the number of queries to optimize (effectively 
disables NCQ optimisation) to 1:
echo 1 > /sys/block/sdx/device/queue_depth