RAID suggestions...
Bill Davidsen
davidsen at tmr.com
Fri Jan 5 00:36:05 UTC 2007
Ashley M. Kirchner wrote:
>
> I'm looking at setting up a RAID system for doing video work. My two
> main requirements are speed and reliability. Speed is an issue because
> of the constant streaming of hundreds of megabytes, if not gigabytes of
> data that is inherent with video. And obviously reliability, I want to
> make sure I don't lose any data of a drive crashes on me. This will
> also be a hardware RAID solution (as opposed to software) and, depending
> on funds, I may try to make it a hot-swappable system.
fast - reliable - inexpensive. pick two.
But unless you are running multiple video feeds into the disk at one
time, fast isn't an issue. Commodity SATA drives will do 50MB/s without
effort, and 200MB/s is readily reached using software RAID. If you want
fast and reliable, go SCSI. Until recently I ran 20+ servers for an ISP,
with 6M users, and 2-6TB/server. There isn't a non-SCSI RAID card I can
recommend (that does NOT mean they don't exist, I just didn't find one).
If 150MB/s write and 200+ read with good reliability will do, go
software RAID-6 for the data, RAID-1 (three way if you're paranoid) for
the o/s and swap.
Hardware RAID is very good, but the "firmware RAID" on motherboards and
cheap controllers are not usually fast OR reliable enough. Use a lot of
memory. No, more than that.
>
> Based on all the different RAID levels out there, what does the
> collective suggest? 1? 3? 5? 0+1?
>
cheap: RAID-5
reliable: RAID-6+hot spare
fast and reliable: RAID-10+2xhot spare, RAID-1 for bot/root/swap
For SCSI I have had good luck with the "ServeRAID" IBM controllers.
They're Adaptek with IBM firmware hacks, I believe.
--
Bill Davidsen
He was a full-time professional cat, not some moonlighting
ferret or weasel. He knew about these things.
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