On Mon, 13 Oct 2008, Bill Davidsen wrote:
Over a year ago I mentioned RAID-5e, a RAID-5 with the spare(s) distributed
over multiple drives. This has come up again, so I thought I'd just mention
why, and what advantages it offers.
By spreading the spare over multiple drives the head motion of normal access
is spread over one (or several) more drives. This reduces seeks, improves
performance, etc. The benefit reduces as the number of drives in the array
gets larger, obviously with four drives using only three for normal operation
is slower than four, etc. And by using all the drives all the time, the
chance of a spare being undetected after going bad is reduced.
This becomes important as array drive counts shrink. Lower cost for drives
($100/TB!), and attempts to drop power use by using fewer drives, result in
an overall drop in drive count, important in serious applications.
All that said, I would really like to bring this up one more time, even if
the answer is "no interest."
--
Bill Davidsen <davidsen@xxxxxxx>
"Woe unto the statesman who makes war without a reason that will still
be valid when the war is over..." Otto von Bismark
--
To unsubscribe from this list: send the line "unsubscribe linux-raid" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Bill,
Not a bad idea; however, can the same not be acheived (somewhat) by
performing daily/smart, weekly/long tests on the drive to validate its
health? I find this to work fairly well on a large scale.
Justin.
--
To unsubscribe from this list: send the line "unsubscribe linux-raid" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
