SAS 300gb vs. Raptor 300gb? thoughts?

Discussion in 'Mac Pro' started by rmpstudio, Mar 16, 2009.

  1. rmpstudio macrumors member

    Joined:
    Mar 15, 2009
    #1
    I would like to set up a RAID0 raid with either "2x 300gb SAS" or "2x 300gb Raptor".

    First, is it possible to do so with SAS?

    Does anybody know which is faster? more reliable? better?

    SAS is 15k rpm and Raptor is only 10k but i don't want to oversimplify :)

    thanks
     
  2. Umbongo macrumors 601

    Umbongo

    Joined:
    Sep 14, 2006
    Location:
    England
    #2
    You need a hardware RAID card to use SAS drives in a Mac Pro if that makes the decision simpler.

    This link might help from a performance difference.

    The SAS drives are probably more reliable, but I wouldn't think it would impact you. You might want to consider SSDs too if you haven't already. Especially if noise is an issue as SAS drives and raptors are loud.
     
  3. rmpstudio thread starter macrumors member

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    Mar 15, 2009
    #3
  4. rylin macrumors 6502

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    Aug 18, 2006
    #4
    Another day, another post :(
    Mr. OP: please be aware that if one of your disks in a RAID-0 die, the entire array dies, taking your data with it.
    If you still want to run RAID-0, make sure you have a solid backup strategy.

    For more info, feel free to look through the threads on the first page or search for posts by nanofrog or myself.
     
  5. nanofrog macrumors G4

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    May 6, 2008
    #5
    Velociraptor's are quiet. I can't even hear mine, and the system stays at 20dBA (case & cooler fans).

    It works in the Mac Pro. Results: No Problem. :p
    BTW, other members have them, and seem to be quite happy with them.

    As for running it in RAID 0, please pay close attention to rylin. It offers a cheap speed boost, but it has no redundancy whatsoever. So if any drive fails, ALL DATA IS GONE.

    If you still choose to go this route, make absolutely sure you have an adequate backup system.
    Absolutely. :D
     
  6. Horst Guest

    Joined:
    Jan 10, 2006
    #6
    VelociRaptor HLFS drives are the ones which are backplane ready and fit the MP bays; Raptors are different drives, btw. .

    As for RAID0 , if one drive fails, all data is gone.

    With a single drive, if one drive fails, all data is gone.

    Where's the greater risk with Raid0 ?
    The chances that one of the drives in a Raid0 is a lemon and goes belly up prematurely increase with more drives being involved.

    But you need a backup solution in either configuration,and in the end the likeliness of a drive going down is pretty much the same.

    Running a Raid0 array is by no means risky, that's a myth from the PC world, but not backing up very much so.
     
  7. iBug2 macrumors 68040

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    Jun 12, 2005
    #7
    If you have 2 drives and 1 drive fails, not all data is gone. Just the one in your failed drive. In RAID 0, one fails = all fails.
     
  8. nanofrog macrumors G4

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    May 6, 2008
    #8
    The way rmpstudio posed the question, I presummed he meant with new drives, so it translated to the Velociraptor to me. ;)

    With RAID 0:
    FAILURE RATE = n*UBE (single drive)

    n is the number of drives, and UBE is the Unrecoverable Bit Error rating of the drive used. If the array is composed of mixed drives, it's based on the lowest. (Weakest link).

    So the failure rate is actually higher than that of a single drive. Keep in mind, RAID is hard on drives, particularly consumer models. You can get lucky and the drives seem to last forever (next machine anyway), but I've seen them die in under 2 months on multiple occasions.

    Failure rates are only going to get worse (increase), as the platter density & capacity increases. Drives at 334GB/platter already exist, and they'll only get higher.

    Enterprise drives help, as they have a UBE of 1E15 vs. 1E14 for consumer drives. The vibrational tolerances, specialized firmware, and a few other tricks help, as they're designed for RAID.
     
  9. rmpstudio thread starter macrumors member

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    Mar 15, 2009
    #9
    Didn't know that.. thanks for the heads up.

    I understand exactly what a RAID0 is designed to do. I am planning on using it as a temporary place to import and process photos and then i am going to transfer the files to my 1TB hard drive. The Velociraptor RAID0 is only going to be used for workflow and will be erased (for the most part) afterwards.
     
  10. sboerup macrumors 6502

    Joined:
    Mar 8, 2009
    #10
    Check out the barefeats comparison for the best boot drive for OSX.

    I would personally skip the 300gb Velociraptors and go straight for the 6400aaks, which is about 12% slower than the Velociraptors, and less than 33% the cost.

    I have 2x640gb drives in RAID0 and currently get 210mb/s read/write. It's fast. But, you need to have a backup setup diligently. Time Machine will work great, but also making a disk image every day will be better. I do both.

    I let Time Machine run the backups hourly, then every night CCC will update the disk image onto the same 1TB drive that Time Machine uses.
     
  11. rylin macrumors 6502

    Joined:
    Aug 18, 2006
    #11
    Then you'll love it :)

    In general, increasing local IO will give you a bigger performance boost than anything else.
    I'm probably just a bit jaded because it seems there's a thread about R0 pretty much every day ;)

    In other words, for scratch data, R0 (and R1!) can be awesome, but you'd definitely want a good backup strategy with it.
    It sounds like you've thought this through, so I'll make a mental note not to bug you about "R"AID-0 :p
     
  12. zmttoxics macrumors 65816

    zmttoxics

    Joined:
    May 20, 2008
    #12
    You could do raid 0+1 or 1+0, but I believe you need 4 harddrives for those configurations. They way this works is the first 2 are striped for speed, then the last two replicate the first too leaving you a restore solution. You could also getaway with it if you invested it a time machine like backup solution.

    If your into ZFS you could also do a ZRAID which is always fast because ZFS is awesome. :D
     
  13. PowerPaw macrumors member

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    Jan 15, 2009
    #13
    Another option if you are concerned with RAID0 (hey a single drive on a single drive setup can fail too, its just half as likely to happen) is to use Timemachine to 'asynchronously replicate'/backup to the stock drive that came with your Mac Pro if its big enough.

    At the end of the day you should be pulling off an off-line backup to say a FW 800 drive on a regular basis anyway.
     
  14. Horst Guest

    Joined:
    Jan 10, 2006
    #14
    Thanks, wasn't aware of that .

    I'm also using my Raid0 array for scratch and temp. work files only, so backups are simple and possible damage not hurtful; the performance is excellent for Photoshop, compared to a single HDD solution.

    As said above, it might be worth considering the WD 640 Black instead of the expensive Velociraptors for now, and look into SSD drives once they are affordable and time-proven.

    For system/apps the Velociraptor is really nice, though, I'm using a single 300GB VC for that.
     
  15. bozz2006 macrumors 68030

    bozz2006

    Joined:
    Aug 24, 2007
    Location:
    Minnesota
    #15
    i concur in regards to backup strategies. I will shortly be purchasing 2 150GB velociraptors for a boot volume, and I feel comfortable with no fewer than TWO backups; i'm doing one with time machine, and setting superduper! to clone the boot volume 4 times/day.
     
  16. nanofrog macrumors G4

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    May 6, 2008
    #16
    The Velociraptor is a nice solution for a faster, single drive, particularly for an OS. It happens to be a good alternative for a MP, as the HDD's are limited.

    Other than that, cheaper drives in RAID would make more sense. But 4 - 6 drives in a MP makes that difficult, and and it's even worse on the '09 model, as you're effectively forced into an external solution. Unless you can live with Apple's RAID card, and a max limit of 4 drives for an array. It limits performance and expansion.
    I presume you intend to use RAID 0 on the VR's. The quickest way to go (SATA, non-SSD), and have a backup. The second backup isn't necessarily a bad idea, but some might think it's a little paranoid. ;) :p

    You might want to think about RAID 10 though, and an external backup drive. It can offer performance, and the mirror would be nice as well. (Keeps the OS/apps available with the fault tolerance it provides). Something to think about at any rate before you leap on the VR's. :) It can also provide more capacity.

    For a mixture of speed/capacity, you might want to take a look at the RE3's by Western Digital. Not bad at all. ;)
     
  17. bozz2006 macrumors 68030

    bozz2006

    Joined:
    Aug 24, 2007
    Location:
    Minnesota
    #17
    That is something i'm looking into (RAID 10). I think i will ultimately go with the two velociraptors as my boot drive doesn't require much space, as i don't store any data on my boot drive. If i do a RAID 10, should the mirror drive be of the same model as the striped drives? Like, would it be OK to use the two VRs striped, then mirror with a 500GB WD Caviar?

    edit: Can RAID 10 be set up in disk utility? all it says is striped or mirrored... or would i set up the striped array, then use that striped array and set up a mirror with the 3rd drive after striping the first two?
     
  18. rylin macrumors 6502

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    Aug 18, 2006
    #18
    IIRC, R10 is only available in OS X Server.
    Feel free to correct me though :)
     
  19. nanofrog macrumors G4

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    May 6, 2008
    #19
    If you go RAID 10, you'd want to use it for more than just the OS. That's a waste, given the MP's limited drive bays, IMO. When I mentioned it, I was thinking OS + applications at a minimum. Data would be up to you, but again, the limited HDD bays would make placing everything on the array attractive.

    As for the drives, you don't have to use identical drives, but you'd potentially end up with "wasted" capacity on the 500GB drives. Normally, you can partition them, and be able to use the remaining capacity. But I've not done this with OS X, so I'm being cautious. It's likely possible, and would be surprised if you can't, but it's possible.

    Others who may have done this can tell you for sure. ;)

    RAID 10 is possible in OS X, according to specs I've seen (OS X). You'd make the two mirrors first (RAID 1) consisting of (VR150 + 500GB WD), and then stripe the two (RAID 0).

    If you go in the reverse order, stripe first, then mirror the two stripe sets together, you'd have a RAID 0+1 (or 01). Not quite as secure, so be sure you make what you actually want. ;)
     
  20. bozz2006 macrumors 68030

    bozz2006

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    Location:
    Minnesota
  21. nanofrog macrumors G4

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    May 6, 2008
    #21
    :cool: No problem. ;)

    Hope it helped. :D
     

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