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Re: RAID suggestions...



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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