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

[Edward Middleton <emiddleton@example.com>]

Jason Hall wrote:
>> As long as one has a drive that is identical in specifications, might it 
>> not be a good idea to not have identical brands?

No because it isn't just the specifications it is also the caching
algorithms.  The other issue is that hard drives made around the same
time probably have parts sourced from the same manufacturers so it may
not make any difference.

> Identical drives is more of an issue with hardware raid - where the
> controller handles the I/O. Generally, hardware mirroring means an exact
> duplicate between the drives - partitions and all.

Well obviously if you use a different partition scheme on your software
raid you will defeat any advantage of using identical drives but this is
the case whether you are using hardware or software raid.  The problem
is the read and write performance varies depending on where on the disk
you are writing.   With raid1 you have to write to both drives so the
write performance can't be better then the slowest drive.

If you are going to bother with raid you should also be using S.M.A.R.T
so that you get advanced warning before a critical failure.  It would
also make sense to buy drives designed for raid.  Seagate drives come in
desktop varieties with names ending in AS and raid varieties ending with
names like NS.  I gather the AS firmware versions are tuned for
performance while the NS reliability.

Edward