[ILUG] Why RAID
paul at clubi.ie
Tue Jul 13 13:22:50 IST 2004
On Tue, 13 Jul 2004, Paul Mc Auley wrote:
> likely to recover from a serious disk failure, and doing stuff in
> the main CPU rather than on a dedicated controller is going to
> generate overheads.
CPU overhead is negligible. Indeed, it can be a win for RAID5, an
Athlon or any other modern CPU will beat the pants off any of the
CPUs used on mid->high end RAID controllers.
The overhead for host-based RAID is mostly bus overhead. You have to
transfer data n times to controller(s) rather than once.
Apparently the Promise SX4 SATA controller is flexible enough to be
able to solve this problem. From what I gather from l-k, it's sort of
a RAID "accelerator" rather than an actual RAID controller - XOR
engine and memory but leaves the host to drive RAID logic. So once
Jeff Garzik and Neil Brown work out how to support this with
linux-raid it will be the controller to have ;)
Paul Jakma paul at clubi.ie paul at jakma.org Key ID: 64A2FF6A
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