On Tue, 2003-02-11 at 09:16, Steven Dake wrote: > I don't know the specifics of those cards, but if they include an i/o > processor, they are a hardware RAID. > > Keep in mind that unless you want to boot or use a RAID 5, or want to > share your RAID volumes between different operating systems, there is > little reason to purchase a hardware RAID card. Software RAID is quite > sufficient for most needs and the host processor running at 2+ ghz is > much better at RAID then a 60 mhz i960 IOP. Keep in mind, though, that > hardware RAID adaptors have built in xor accelerators which can do > multiple xors in one instruction in hardware, allowing for much better > xor performance then the intel or ppc processor can do. While the performance of RAID 5 using software RAID is generally far superior to that provided by hardware RAID, host CPU usage can be -quite- high in high-load situations. The benchmarks recently posted had cpu usage numbers at over 90% on most sequeential writes and reads. Greg
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