> this differently). I've only tipped the ice berg of info here and
> I'm sure Adam Thompson will fill in the bits I've missed. :)
Err... no, I think you've covered it quite sufficiently!
The obvious exception being ZFS arrays, where hardware RAID controllers are pretty much useless and just get in the way.
> I'd also recommend avoiding as much RAID as possible that's not
> controller independent mirroring.
Unless you meant to stay away from hardware RAID controllers altogether and use software RAID?
That pendulum swings back and forth regularly.
RAID 6 warrants (in many cases) a dedicated processor... either by running a dedicated storage array with, e.g. ZFS or Linux MD in raid6 mode, or by using a hardware controller that does RAID 6 onboard.
RAID 5 gives the best TB/$ but suffers a write performance penalty, and an everything penalty when in degraded mode.
RAID 1 gives the worst TB/$ but the best performance all-round.
Whatever you do, a BBWC (battery-backed-up write cache) will enable much better performance. This is typically a hardware thing, but it can be simulated in software too if you have a UPS and you otherwise trust the solid state components of your motherboard, CPU, RAM, etc.
So, if you use software RAID, make sure you have ECC RAM and a good UPS (that gets tested regularly).
If you use hardware RAID, shoot for RAID 6 native support and a BBWC.
[Yes, I know I'm getting off-topic from Kevin's original post.]
-Adam
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