On Fri, 14 Nov 2008, Billy Crook wrote:

Obviously RAID-class drives benefit in hardware raid (with hardware
raid controllers).  But do RAID-class drives benefit when used on a
non-raid hardware controller, with linux software raid (mdadm)?  What
about a hardware raid controller in JBOD mode?

This is not a HW vs SW issue, it has to to with the behaviour of the 
drives in conjunction with the OS when a certain thing happens.

In a non-raid environment, you want to read the data at any cost, so 
waiting 2 seconds for it to read is no real problem, you just want the 
data.

In a raid environment you can reproduce the block by way of mirror or 
parity, so you want the read to fail after a short time so it won't delay
the reading of the data.

So as long as md can re-write a faulty block (which it can from 2.6.15 (or 
.16 or .17, I don't remember), you should have raid firmware in your 
drives for best performance.

-- 
Mikael Abrahamsson    email: swmike@swm.pp.se