Striped RAID gets it performance improvement from overlapped I/O:
Drive 1 is transferring data while drive 2 (and possbly 3) are moving the heads to get to the next stripe.
Anything you do that moves the heads away from the primary file adds all that overhead back in and wrecks the performance of the RAID. That is why there is such a remarkable overall performance boost from establishing a Boot Drive -- seeking to get a system file or do same paging no longer intervenes in your data files reads. The drive heads are not distrated from the data area.
If you are doing Photo processing, you are often reading an input file and wring an output file. Placing both of these on the same RAID will provide far less performance than expected, since every Source read competes with every Destination write, and the drive heads are moving every time you change.
The other issue you may not be facing is that if a Striped RAID loses a drive, you generally lose everything on the entire array. It would be better to think of a striped RAID as a fast, temporary starage place, that needs to be backed up fairly quickly.
Thanks for your reply. If I'm understanding you correctly, it sounds like you would suggest a fast single drive like a Hitachi 4 TB (7K400) or Seagate Barracuda 3 TB for my Data volume, rather than a striped RAID?
I have Time Machine, daily backups on-site and Crash Plan (off-site backup daily) so I'm pretty well-covered in terms of data protection.
First, you need enough RAM, which you probably have. This gets you out of Photoshop's "scratch drive" problems.
Then a Boot Drive, to keep the system "snacking" after a bit of this or that from wrecking your data performance.
Next a Source drive or array AND a Destination drive or array.
Then a backup plan.
If you are keeping an array, it may better to have the Destination on the array. Then the only files with real backup urgency are the destination files.
When stripe arrays for scratch were a must, moving your project to the array was found to be faster.
Writing a 2GB file - depending on file type - could be horrible too, and outputting to stripe array could speed and ease that up.
Having an SSD for projects / scratch can help.
Even having source files on an array meant you could load large images quickly as well.
I doubt most need or want what MacPerformanceGuide shows with a PCIe SSD, 4 x 4TB drives in an array (using HALF, short stroke partition array to keep I/O seeks short and maximum speed). OWC has come up with 480 and 960GB SSD kits.
There are a couple of benchmark utilities - you supply stopwatch - to test system configuration.
http://www.macgurus.com has had photoshop storage and optimizing guiide and test program
I am 100% positive I posted and you asked the same a week or two ago, the 750GB WD Blue units for instance, and suggesting WD 10K drives instead, or WD 2TB ($169 each again finally).
8 DIMMs all the slots used of course for peak memory (drops 17% if using fewer slots) so 4 x 4GB and 4 x 2GB to get to the 24GB 'sweet spot'
64-bit kernel mode.
CS5/6 and 10.7.4 w/ GTX 570 provides a kick and makes use of CUDA - and only needs two 6-pin power connectors.
I already have an SSD as boot drive with OS X and applications (the OWC 240 GB Accelsior, which as I understand it is a 2x 120 GB RAID on a PCI card).
What I don't understand is how I'd separate source and destination files on two different drives when using Lightroom or Photoshop. I don't even get how that is possible. With Lightroom there are only three files of concern: catalog, previews and image files themselves. They have to be on one drive; they can't be split up on two different drives. Am I misunderstanding your "source" and "destination" drives?
I thought you suggested WD 10k drive instead of the Mercury Accelsior as a boot drive. I need larger capacity drives for my Data drive (with pictures, music, video, docs). Sounds like you're suggesting the WD 2TB drives in a RAID0 configuration? Any reason not to do the Seagate Barracuda 3 TB drives instead, which are also $169 and perform very well according to Tom's Hardware Reviews (http://www.tomshardware.com/reviews/4tb-3tb-hdd,3183-16.html)?
The main question I have at this point is whether to use a single high capacity drive for Data or a RAID0 of mid-to-high capacity drives.
Regarding the GTX 570: I've never understood which aspects of Lightroom/Photoshop performance are GPU dependent, which are CPU dependent, which are storage speed dependent and which are RAM dependent. To simplify: what benefits would I expect to see with a GTX 570 in photography use if I'm not a gamer?
1TB $300 10K VR or three to four. = for RAID my friend. Want an alternative non-SSD as you asked about SSD and reliability etc and if SATA III was "waste" or not able to use performance. Same goes for the OWC PCIe card it seems for some. And 10K 250GB $150 same prce and still excellent boot drive (I cannot tell when I booted from SSD or when I use WD 10K!)
I do use an SSD for my photo project drive and I do like SSD there. MPG uses 'everything" with SSD + PCIe AND uses 4 x 4TB Enterprise drives (@ $390 each)
Want Enterprise, those are. These :
Amazon customer feedback : I'm not normally a fan of SATA drives, I've worked extensively with SAS/SCSI drives for servers/etc for the last 20 years and only used ATA/SATA when required. Still, I've had some projects come up recently where the only option was SATA and high capacity was required.
After some bad experiences with the WDC Cavier Black 2TB, I gave the RE4 a try. It's been great. I've now had 5 of them running for the last six months and the SMART monitoring reports still show the drives as in almost new condition...no errors, no need for sector changes, no unusual increases of load cycle counts, etc. Performance has also been very good....surprisingly good for a mere 7200rpm device. Not to mention, the drives seem to work nicely in both software and hardware raid. I'll probably end up buying another 5 of them soon.
Hitachi Ultrastar 7K3000 is the world's first and only 7200 RPM hard drive rated at 2.0 million hours MTBF and backed by a five-year limited warranty.
Thanks so much, hatter.
Just to clarify: you're using a large capacity SSD for your image drive? I never considered the possibility of having my music/docs/video on an HDD (maybe a 2 TB RE4) and my images on a high-capacity SSD (i.e. 960 GB).
The disadvantage of that plan, however, is that 960 GB SSDs are >$1k!