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View Full Version : OS X RAID and Hardware RAID for Mac Pro




PowerMike G5
Nov 22, 2006, 11:40 AM
I'm currently running a 2x500GB RAID 0 configuration in my Mac Pro which I use for media scratch disk and such with Final Cut Pro. I was thinking of adding a 3rd 500GB HD into the mix and run it all in RAID 0. Is there any difference between the software RAID in OS X and a hardware RAID, like one made by Caldigit? I am thinking of using it as a capture RAID for capturing uncompressed video or capturing uncompressed and converting to a codec on the fly.

Is there really any difference between running RAID in OS X than through a dedicated hardware controller?



jsw
Nov 22, 2006, 11:44 AM
Yes - a "real" RAID will handle the throughput locally, meaning OS X doesn't (taking mirroring as an example) send twice as much data as necessary (one set per drive), thus effectively halving your bandwidth. And there's no CPU drain (which is, admittedly, negligible anyway).

I have a number of external drives RAIDed via OS X, and I've seen some issues. It works well enough (except for some suspicious crashes...), but a hardware RAID is better if you need speed or don't want to have to even think about a CPU toll. OS X RAID is fine for backups, media files (for listening/viewing, as opposed to editing), etc.

gammamonk
Dec 23, 2006, 10:55 AM
Apple's Disk Utility doesn't allow you to do Raid 5, which is what it sounds like you want. You can't mirror three drives together.

I just spent yesterday setting up a Slackware Linux machine with 4x320gig drives in a RAID 5 config. The raid built overnight, it took around 6 hours. But when I went to format it, it said one of my drives had failed. After a reboot, no drives detected at all. F that. So I pulled the drives out of that box, threw them in my mac, did RAID 0 on them. They work just fine. I lose 320gigs of space, but it was setup in about 2 minutes. I can live with that.

After I read up on it a little more, I might do RAID 10, which Mac supports. This gives you full redundancy and a 200% speed increase. (With a 4 drive setup)