On Feb 26, 2007, at 11:26 PM, Andrew Lentvorski wrote:
You don't want a parity striping RAID (5 or 6) if you value write
performance.
NetApp can get away with it because they have nice battery-backed
caches that reorder and hide the whole read-modify-write cycle
required with parity striping. In addition, they have hardware
accelerators to hide the XOR required to generate the parity stripe.
If you're going software RAID and care even remotely about
performance, you want either RAID 1 or RAID 1+0, not RAID 5 or 6.
Well, isn't that the whole point of taking advantage of a hardware
raid appliance? If you want speed AND reliability, and have money,
you buy the hardware that ensures you have both.
If you don't have money, you can spend a little less with software
RAID 1+0 (a.k.a. RAID 10).
Though, if you're building a fileserver that's not going to be doing
anything other than file serving, feel free to waste as much CPU as
you want on software RAID to get the overall benefits that you want.
Even buying the cheapest Core 2 or Xeon (or Athlon 64 or Opteron) you
can find, you'll never use the full power of the CPU package just
serving files. Might as well put it to use ensuring data reliability.
:)
Gregory
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Gregory K. Ruiz-Ade <[EMAIL PROTECTED]>
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