Mikael Abrahamsson wrote:

On Fri, 14 Nov 2008, Billy Crook wrote:

quoted

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.

Here is a paper about the Western  Digital feature "TLER", which is used 
in all their RE series RAID drives.

http://www.wdc.com/en/library/sata/2579-001098.pdf

In addition, these drives are better able to cope with the problem of 
mechanical vibration/resonance that occurs when multiple drives are 
mounted in close proximity:

http://www.wdc.com/en/library/sata/2579-001079.pdf

These features will benefit HW and SW RAID implementations.

I have no association with Western Digital, other than as a satisfied user.

Regards,

Richard