[H-GEN] I was once sent a link spelling out the evils of RAID5...

[Rick Phillips]

Gary, the following is an email from David Jerico.  I think this is the
one you are after.

Regards,

Rick Phillips (who never throws an email away.
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Gary Curtis wrote:
> Size wise, I'm thinking 3x320Gb disks in a RAID 5, plus a
> single disk for the OS. Not that fussed about mirroring the
> OS disk. I would spring for a hot spare in the RAID if the
> combined IQ of HUMBUG thought it was wise.

Disk so embarrassingly cheap now days, just buy two of everything.

No, really.

Choose a good case with a top vent, and a bundle of drive bays across
the front (the ThermalTake Armour series are a good example), and buy
two of every hard drive.

Buy at least another one as a hot spare.

RAID 10 with a hotspare only requires 5 disks for the same capacity as
you've mentioned above (and only $260 more). The result is an array
that's not only faster on reads, but significantly faster on writes,
doesn't suffer the problems of RAID 5 with respect to parity during
recovery, and has an order of magnitude higher reliability.

Disks will die. Don't risk your data on RAID 5.[0]

As for SATA RAID controllers, my experience has given me two solutions.
The first one is a SAN, the second one is 3ware. Outside of that, just
use software RAID. As Stephen correctly pointed out a lot of the onboard
controllers are just hardware assists, and as such will suffer the same
problems as a software RAID array during a failure event.

[0] http://www.baarf.com/ is a good  source of info on why RAID 5 sucks.

-- 
David Jericho
Senior System Administrator, AARNet
Phone:     +61 7 3317 9576
Mobile:    +61 4 2302 7185