Need Opinions on RAID as startup disk

Discussion in 'Mac Pro' started by designillinois, Nov 8, 2006.

  1. designillinois macrumors newbie

    Nov 8, 2006
    I recently purchased a mac pro and have outfitted it with 4 internal 300GB hard drives, with the thought of setting it up with a striped RAID array to boost speed of opening and writing large Illustrator and Photoshop files.

    Would you recommend installing the OS and Apps on a raid setup and with the 4 drives, what would be the best configuration. Currently I use 2 HDs, one as primary and one to backup files manually until they are archived to DVD.

    Thanks for your help!

  2. LeviG macrumors 65816

    Nov 6, 2006
    Norfolk, UK
    Personally (coming from a pc user perspective admittedly) would not bother with a striped array for illustrator/photoshop, would most likely go mirrored for redundency. I would probably set up the mac pro in the below config (this is the likely route I will take when I eventually buy a mac pro)
    disk 1 - os-x
    disk 2 - xp pro/vista - I need windows for some of my programs
    disk 3+4 - mirrored raid array for storage, the speed of reading is comparable to striped array although the writing is slower.

    If not using windows use the 2 disk for a seperate storage drive, ie for non critical files etc
  3. designillinois thread starter macrumors newbie

    Nov 8, 2006
    I read in a Mac magazine that the RAID would give a rather significant speed boost as the data is being written simultaneously to 2 drives rather than one. I really don't want to mirrored setup, since I like to backup my files myself.

    Has anyone setup their startup disc as a RAID or just secondary storage drives?
  4. jaguarx macrumors regular

    Jan 5, 2003
    There's some numbers on OSX's SoftRAID here

    In short, there's a boost but nothing to write home about. You need hardware RAID for a serious speed boost. Might want to consider investing in a Western Digital Raptor 10000RPM drive for scratch and current working files, that'll give you a real speed boost.
  5. LeviG macrumors 65816

    Nov 6, 2006
    Norfolk, UK
    My previous pc was set up with a hardware based raid 0 (striped array) and I tried it with both storage (video and photoshop) and boot. Personally I saw no real performance gains using it in that way over plain old single drives.

    My fileserver is currently using a raid 3 storage solution purely due to redundency nothing more.
  6. ironjaw macrumors 6502

    May 23, 2006
    Cold Copenhagen
    There is a thread at Apple Discussions specifically discussion RAID performances and some tests from Bearfeats. Do a serach there on RAID preferably under the Mac Pro section.

    You'll find some great advice on those issues. I'm too lazy to go there myself :p
  7. ChrisA macrumors G4

    Jan 5, 2006
    Redondo Beach, California
    The probability of a failure goes up by a factor of four if you go with a 4-way stripped RAID. Basically is any one disk fails you loose all data. The only data that should go on a stripped RAID is temporary working data. Never importent stuff.

    Conversly on a mirrored RAID the chance of failue is only 1/4 that of a single disk.

    If you have four disks your best option is to use RAID5. Not only do you gain some performance but you can continue to run with one failed drive
  8. ChrisA macrumors G4

    Jan 5, 2006
    Redondo Beach, California
    That PC likley could not do parallel reads and writes to both disks of the array. The Mac Pro does have 4 independent SATA channels.
  9. aneks macrumors regular

    Aug 29, 2006
    I recommend not running RAID as boot.

    I have four drives in my mac pro:
    1 : 250 gb (default apple) boot and os
    2&3 250 gb (Maxtor) RAID 0 or striped footage for Shake.
    4: 320gb (seagate) for win xp

    runs very happy, except I cant see the RAID in winXP. I also use a lacie 500gb fw800 RAID to back up my internal array for safety.
  10. LeviG macrumors 65816

    Nov 6, 2006
    Norfolk, UK
    It could, it was based around a server motherboard with dedicated onboard raid controller, completely seperate to the rest of the hd/optical ports, plus I could watch the little graphics on the utility as they worked :)
  11. CanadaRAM macrumors G5


    Oct 11, 2004
    On the Left Coast - Victoria BC Canada
    I don't favor the idea of RAID 0 - it's risky, and the real world benefit - other than servers and saving high volume data streams like video - is slim to none.

    I am convinced that you get more of a benefit by splitting your function among 4 separate, non-RAID drives.

    OS (OSX Boot disk)
    Scratch disk (the Photoshop scratch files)
    Applications (the Photoshop program files)

    The nature of the software is that it is constantly flipping between reading data, reading and writing scratch, reading program, reading and writing writing scratch, writing data, repeat ad infinitum. A limiting factor in performance is pausing between each of these functions, for the disk head to move across the platter and locate the first block of the data to read write. If all of the functions are on one drive, then the head spends a lot of unproductive time zinging back and forth.

    By separating the functions onto different disks, each with its own set of heads, the heads can remain in place over the particular patch of data, and head transit time is minimized. You want to test this out, take a large folder, and Duplicate it in place. Time it. Then take the same folder, and Copy it to another physical drive. Time that. Copying to another drive is far faster because there are two sets of heads at work

    Note that partitioning a drive into multiple partitions does not get the benefit, because it is still the same heads that have to read and write the different partitions on the drive.

  12. THX1139 macrumors 68000


    Mar 4, 2006
    I agree that RAID 0 is risky, but only because you are splitting the data across two or more drives, and with more drives, you're statistically increasing your odds of data loss. However, since you are splitting the data, you are pratically doubling the ability to write data to disk. That's where RAID really shines. Like you said, video or Photoshop scratch or any other streams of data.

    I disagree that the benefit is slim to none. If you setup RAID using drives designed for RAID environments AND use the drives to only hold working files (that are replaceable), then you can really see the benefits. I think a good setup would be to have a main drive for OS and applications, another for main storage or Window, and then two drives setup as RAID. The RAID drives would only be used as scratch and holding temporary working files.

    For the average user, then yes, RAID is not a good solution. Especially if they are planning to use the RAID as the primary storage or data drive. And especially if they plan to setup the RAID as primary boot for everyday use.

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