RAID (was: RE: [geeks] New Itanium machines from SGI)

[Gavin Hubbard]

>Hmm, I actually think that Software RAID on Linux kicks some serious
>ass.  The only other implementation that I've used heavily is on NT, and
>that one blows goats.  Anyway, the Linux software RAID implementation is
>faster than Dave chasing a pretty girl.  It easily outstripes any and
>all of the PCI based RAID solutions that I've been able to get people to
>run benchmarks on.  Using RAID 5 on modern CPUs uses code tuned to fit
>into L1 cache, making the checksumming FAR faster than you can hope to
>deliver from disks.  RAID 1, 0, and 10 don't show up as being any faster
>or slower than the PCI based RAID cards (the differences are within the
>margin of error for my testing).  Booting from RAID 1 works and is
>pretty well tested.  Software RAID also offers you the flexibility of
>working with slices (err, partitions, whatever) instead of whole disks
>(I've never seen a hardware-based solution that worked this way).
>Anyway, I think software RAID is a clear winner for -small- RAID arrays,
>meaning no more than a couple dozen disks, and maybe a TB of moderately
>use.
>	Greg

What were your observations on CPU utilisation for the systems you were
benchmarking? Surely you don't get all that software-RAID goodness for free?

Regards,

Gavin