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ChrisC

Am I wrong to software RAID

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Hi all - I've got a spangly new MacPro arriving in a week or so (hurry up TNT...), and a set of tasty HD's (3 x 1Tb WD Caviar Blacks) ready to pop in it. My plan is to use the installed (640Gb HD) as the boot/application, volume, a second HD for general project/resource storage, and make the 3rd and 4th a RAID-0 set purely as a fast scratch/capture/working drive, using software RAID. Backup will go elsewhere.

 

But then I come across some 'know your RAID' feature in some sales catalogue somewhere saying how software RAIDs aren't worth considering, they'll punish you with CPU overheads that negate the access speed increase, and that if you consider doing something so dumb then you're clearly some kind of retard and shouldn't be allowed to play with the big boys.

 

So... is what I'm planning a bad idea, should I fork out for a RAID card and just deal with it, which is clearly what the catalogue was aiming at? The work is mostly 3D going into either AE or photoshop, often 32-bit, occasionally HD or beyond.

 

Cheers for any advice - C

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I have more or less the exact same setup. I think the RAID card in a Mac Pro at least is something that would be beneficial for a RAID 5 set up with data redundancy. It's my understanding that the RAID 0 or "scary RAID" is still going to be faster that a single sata HD even without a dedicated RAID card. I just back my RAID 0 up every night on an external drive and its not as scary.

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I have the exact same setup. I would be interested in hearing from someone who knows more than me about it. I have not noticed any negative effects of processor overhead, but to be honest, I mostly work on-site at someone else's studio and don't normally do heavy work at home. All I can say is that it works well, but if someone can show me something that proves I'm hurting my performance - I would love to see it.

 

I was thinking about getting the Highpoint Rocket RAID card (I think the 4 port card is less than $200) and actually set the thing up properly. Haven't as of yet. Apparently, the $800 Apple RAID card has a maximum speed limitation as is heavily advised against. That is from www.barefeats.com

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Well one way to look at it - it certianly can't hurt anything. Nothing wrong with having a fast single 2TB volume. And its definately nice to hit the spacebar on a 1080p uncompressed quicktime movie and watch it playback smoothly.

 

I would guess that the nay-sayers you speak of are probably just nerds who have someone else footing the bill for thier dedicated RAID racks, and geek out over the concept of throughput a little too much.

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RAID 0 does not require any additional CPU time, it's RAID 5,6,10 etc. that need more CPU power and are better left to hardware controllers.

The difference is that RAID 0 and 1 don't require any additonal information to be computed and handled.

RAID 0 and 1 are basicaly only slightly different ways to assign the data to the disks.

 

Cheers

Björn

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Great, thanks for the advice guys sure looking forward to that uncompressed playback you mentioned Kurt, I'll report back once it's done see if I can make some comparisons between the RAID and the single disk.

 

Cheers - Chris

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On my system (OS X 10.5.6, 2.8 8-core mac pro, 10 GB RAM), a single 500 GB Western Digital (WD5000AAKS), scores 81,28 in Xbench's disk test. Two of those disks striped together in software Raid 0 score 140,57. So definitely worth it. Just make sure to have an adequate backup system in place, because the risk of data loss due to physical drive failures doubles when your data is spread across two drives.

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The old MacPros actualy have 6 SATA ports from which only 4 are in use. You can extend one of the remaining to a slot in the back and use it as eSATA connector (maybe not hot plug, but faster than any FW or USB conenction anyway). I don't know about the new Nehalem based Macs, maybe they use SATA for the optical drive as well, but even then you have one conenctor left in the standard configuration.

Cheers

Björn

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The old MacPros actualy have 6 SATA ports from which only 4 are in use. You can extend one of the remaining to a slot in the back and use it as eSATA connector (maybe not hot plug, but faster than any FW or USB conenction anyway). I don't know about the new Nehalem based Macs, maybe they use SATA for the optical drive as well, but even then you have one conenctor left in the standard configuration.

Cheers

Björn

 

Or use one of these babies, very nice, now I got a total of 6 disks in my 2008 octacore:

 

http://www.transintl.com/store/category.cfm?Category=2761

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Hi all - just thought I'd report back as you'd all been so helpful, I've got this machine configured now and the extra speed from the striped RAID drives is significant - I've not timed any tests yet but the benefit is immediately visible. I've pulled together a string of 16-bit TIFs into a quicktime movie, they playback OK from the non-striped disk but stutter after 10-15seconds - from the RAID playback is smooth and scrubbing is immediate - it's a tasty setup that's for sure.

 

Thanks for the links about the optical bays too, options are great...

 

Cheers - Chris

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Hi Mousel - are they the Seagate ones? There's some reports of an issue with these, see here for some scary stories. It looks like it might be a firmware issue with the drives, ie fixable.

 

I'm going to be striping (r0) two 1.5 TB drives in my new MacPro next week. Glad to hear of the successful use of the software raid, which I'll be using.

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