Mac Pro Software RAID

Discussion in 'Mac Pro' started by mrgq, Dec 29, 2010.

  1. mrgq macrumors member

    Sep 28, 2007
    I was thinking about purchasing a second WD Caviar Black for my Mac Pro and then configure them as RAID 1+0 (software). My questions are, would i really make a difference in performance being that it would be a software raid? Would i need to wipe out my current Mac OS X installation to be able to make this configuration?
  2. nanofrog macrumors G4

    May 6, 2008
    Please understand, to create a level 10 array, you must have 4x disks. You end up creating 2x separate mirrors (RAID1), which consist of 2x disks each. Then both mirrors are striped toghether (RAID0). Hence 1+0 or 10. ;)


    Performance would be that of a 2x disk stripe set, but it would also have an n=2 level of redundancy (a stripe set has no redundancy at all). It also won't present much of a load on the system either, if that's what you're concerned about.

    Yes. The initialization process wipes out any existing data on the drives in the set.
  3. NoManIsland macrumors regular

    Feb 17, 2010
    I was thinking about doing this exact setup in the bays - would it be possible to use an external Time Machine drive to restore onto the array, or would it have to be a fresh install?
  4. nanofrog macrumors G4

    May 6, 2008
    No, don't use TM.

    But you can use an external disk, and make a clone of the OS, then restore it to the array once it's completed (use Carbon Copy Cloner or Super Duper). ;) Having a clone is a wonderful thing to keep lying around, as it's much faster to get the OS up and running again (means fewer applications, drivers, and OS Updates to install, if any - depending on the age of the clone).
  5. Honumaui macrumors 6502a

    Apr 18, 2008
    my thoughts if you use raid 10 for boot its not the best ? boot does not need that much really a SSD in raid 1 is going to be way way way better and not that much more and still have safety

    I do use raid 10 on our one machine for working files which I feel are more important to keep safe and give some speed to :)

    otherwise raid 1 for safety of a boot if you need it ? many say its overkill ? but raid 10 I would say skip that for your boot and use for data only
  6. NoManIsland macrumors regular

    Feb 17, 2010
    I agree. I'm getting an OWC SSD for a boot drive, and they have 2TB WD Blacks for deadly cheap right now - I have one and I'm thinking of getting three more and setting up a RAID 10 for my general files. Trick is, then I'll need a 4TB + for a TM external. I think it's a good move, though, as right now I have my TM drive in my machine and it's my only backup - that seems to me to be asking for trouble...
  7. nanofrog macrumors G4

    May 6, 2008
    I'm wondering if they're only trying to use the HDD bays, and presume that they're limited to 4x disks only. :confused:

    I agree that an OS on the 10 isn't the best way to use it, and stuffing an SSD (if a fast OS/applications disk is desired and within budget), can be placed in the empty optical bay. No risk of the ICH throttling either. :)

    You could get another pair of 2TB disks and JBOD them in an external enclosure (or stripe, though for backup, I prefer JBOD, as if you lose a disk, you don't lose all the data, just what was on the failed disk). And you should be able to restore that off of the primary data location (odds of a dual primary and backup failure are possible, but not all that likely - usually due to a power problem of some kind when it does). Cheap to do as well (inexpensive enclosure, perhaps Port Multiplier based, and an eSATA card).

    Just a thought anyway... ;)
  8. Honumaui macrumors 6502a

    Apr 18, 2008
    you could use a single 3TB for TM ?

    the theory being even with 4TB you dont want to fill it up all the way ? I say %60 others say less or more ? but once you hit about %60 you start slowing down so the 3TB should do you :) nice and simple
  9. nanofrog macrumors G4

    May 6, 2008
    3TB's are still on the expensive side though, so I prefer the Port Multiplier enclosure, and use more disks (say 8 bay unit, and fill it with 1 - 2TB disks). ;) Cheaper in terms of cost/capacity (enclosure can easily outlast the drives a few times over - just swap them out when they're getting too full in the same enclosure). :D
  10. NoManIsland macrumors regular

    Feb 17, 2010
    Thanks for the thoughts, I can see why JBOD would be better - I was thinking RAID 0 prior to your suggestion.

    I think I just hit a snag: I was planning on putting two SSDs in the lower optical bay, one for OS/Apps, and a larger one for my MIDI libraries, and plugging the drives into the ODD SATA ports. Problem is, I recently heard somewhere (it might have even been you) that the ODD ports aren't bootable - is this true, and if so, how can I work around it?
  11. nanofrog macrumors G4

    May 6, 2008
    Please understand, that if a disk does die in a JBOD configuration, the remaining data will not be accessible as-is. You have to use Data Recover Software to get it (usually save it to another disk). But the point is, the user can do the recovery themselves inexpensively (software's typically ~$100USD).

    I recall some software that claims that it can get the data back from a stripe set, but it didn't turn out well (it's either corrupt due to bad sectors, or the electronics are shot, and there's nothing to recover to begin with, as the data is split in chunks amongst all members). In those cases, you'd need to send out the disks in the stripe set to a Data Recovery Service, and it's expensive (~$2500USD per disk last I checked :eek:).

    Which translates to further incentive to keep a proper backup of your data. :eek: :p

    It was from me. :D

    OS X will boot from the ODD_SATA ports (it's just Windows and Linux that will not, and this is only an issue for the 2008 models - figured you might have missed this little detail :p). This one needed the accentuation to make sure you spot the specifics. ;)

    So you'd be fine running one for OS X and the other the Midi libraries off of the ODD_SATA ports in your system. :)
  12. NoManIsland macrumors regular

    Feb 17, 2010
    Okay good, I wasn't planning on booting Windows or Linux anyways, at least not off the SSDs. Would this affect a virtual machine such as one in Fusion? I have a VM of XP and a VM of 7 that I'd like to be able to still run from the boot/app SSD.
  13. Honumaui macrumors 6502a

    Apr 18, 2008
    true I guess I should have said for time machine the 3TB externals can be had for $170 many places which does not make a bad price solution to start with for a single external drive solution

    but agree PM cases are the way to go and fill up with less $ 2TB for more down the line
    also samsung F4 2TB drives are $79 again at new egg :)

    but I am also getting tired of lots of HDD spinning the noise and heat and power etc.. in our office we have about 50 discs spinning :) I would like to cut that down to half at least
  14. Transporteur macrumors 68030

    Nov 30, 2008
    50 discs? Boy I'd go nuts in there!

    I'd recommend a central storage in a noise dampened cabinet. ;)

    Nothing worse than white noise... horrible.
  15. nanofrog macrumors G4

    May 6, 2008
    I'm with Transporteur; get a sound insulated rack (would also mean some different enclosures).

    The other option is to go with an interface that allows for longer cable lengths and put them in their own room (will definitely cost more though, so it would be worth waiting for a major upgrade for this; DIY SAN, NAS (say 10G Ethernet or FC), or use SAS disks, which allow up to 10 meters).
  16. pantera327 macrumors newbie

    Jan 1, 2011

    This thread goes along with one I started. If I do Raid 1+0 I know I will eventually need an external enclosure. What card would be a cost effective card to keep in mind for my Mac Pro 8 core 2.8 early 2008.

    My thread,
  17. Forker macrumors newbie

    Dec 11, 2010
    Raid 10 is pure overkill for a personal machine
  18. nanofrog macrumors G4

    May 6, 2008
    You need to figure out your capacity and speed requirements. Then consider your budget. With that, the best level can be determined (warning; most new users tend to under-estimate the funds necessary to enter into parity based arrays).

    I'm willing to help, but I've no idea what you're doing.

    Let me know your application usage (not just what you use, but how much time in each), file sizes, capacity you need (think you need, and plan for 3 years worth), and speed if you know (application usage helps here when you don't). Also, if you plan to boot from the array or a separate disk, and if you will run more than one OS on it.

    Depends on what you're doing (especially the budgetary aspect). ;) :p

    For example, if redundancy + modest speed above a single disk are needed, capacity requirements are small (keep it at 4x disks), and budgets are tight, a level 10 array can fit the bill nicely. The reason is, no RAID card is required (OS X can do 0/1/10 under Disk Utility).
  19. Forker macrumors newbie

    Dec 11, 2010
    It is pure overkill for a personal machine... Unless you intend running several virtual machines or heavy database work, io rates even on a raid 5 system which isn't great, is perfectly capable. Raid 10 is typically found in enterprise Database disk subsystems that serve oltp or data warehouses. Retail users wouldn't ever require that throughput.
  20. Honumaui macrumors 6502a

    Apr 18, 2008
    over half mine are dampened and pretty good on quiet everything in the case has changed fans PS etc..

    going to rebuild my raid box with a nice thermaltake heatpipe PS I have around so no fan noise from it and only a super quiet 120 spinning

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