[RndTbl] Hard drives
athompso at athompso.net
Mon Jan 14 11:42:45 CST 2013
> 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!
> I'd also recommend avoiding as much RAID as possible that's not
> controller independent mirroring.
The obvious exception being ZFS arrays, where hardware RAID controllers are pretty much useless and just get in the way.
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.]
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