RAID Questions
2007-12-25 2:48:00
I've been doing some research regarding the degradation you get on
read/write performance across the various RAID's, in one instance I have
seen that even with extremely fast - hardware accelerated RAID
controllers, using RAID 5 gives around a 50% degradation on the maximum
attainable write speed and straight mirroring (no striping) gives a
degradation of around 15-50%.
At present (dont ask why) we have a SAN consisting of two SunFire 3800's
connected to arrays each containing 10x73GB disks (15k rpm), we have
RAID-5 each disk array individually (9 disk pool 1 hot spare in each
array) and then used VxVM to software mirror the individual volumes
across to the opposite disk pack. I want to switch from this to VxVM
mirror as we are using now and RAID 0 on each disk pack/array, so
mirroring across two packs and striping across each individual pack.
What kind of performance increase do you think I should expect from this
based on the information I have given, currently we are getting terrible
performance of around 9 Kb/s (iostat), we cant hardware remote mirror as
the controllers dont support it.
Cheers
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