On Thu, 15 Jun 2000, David Murphy wrote:
> You can have something that's relatively (fast, safe, cheap), pick any
> two. RAID5 is relatively safe and cheap. It's not relatively fast.
grab a couple of identical disks and a machine with a half-decent
CPU. setup linux software RAID. Try:
RAID1 across 2 disks
RAID5 across 3 disks
run your benchmark (i recc'd bonnnie or bonnie++). look at the
numbers: RAID5 will have far better read performance than RAID1, and
/slightly/ better write performance.
What this tell's you:
As long parity calculation is not an overhead, RAID5 beats RAID1
handily for performance. The problem is that older cards, and low-end
new cards have shite CPU's, unfairly giving RAID5 a bad name for
performance.
With a decent card CPU, as on most decent new cards, RAID5 flies.
those are the numbers i've seen, and i have to believe them.
regards,
--
Paul Jakma paul at clubi.ie
PGP5 key: http://www.clubi.ie/jakma/publickey.txt
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