How reliable is the OS X RAID setup?

Discussion in 'Mac Pro' started by wheezy, Oct 3, 2008.

  1. wheezy macrumors 65816


    Apr 7, 2005
    Alpine, UT
    I have 2 1TB drives coming in on Monday, and I plan to put them in a mirror RAID using Disk Utility. How reliable is the OS X software RAID setup? Would I be better to just manually backup from one drive to another?

    The drives will be for my photography, I wanted a mirror setup so I'd finally have a backup of my (current) 250GB's of photos. (Most of which I could probably burn to DVD's but humor me.)

    If the RAID crashed somehow via the software, would the data still be recoverable? I have a MP and will be putting them in Bays 3 & 4.

    Also, is there any benefit to the different block sizes? Since my files will all be at least 7MB would the biggest block size speed it up?
  2. ekwipt macrumors 6502a

    Jan 14, 2008
    I think you'd be better off manually backing up the data.

    Raiding two drives in this method will decrease drive performance
  3. wheezy thread starter macrumors 65816


    Apr 7, 2005
    Alpine, UT
    Really? I've read that it could increase it even just a little bit.
  4. cohibadad macrumors 6502a


    Jul 21, 2007
    Shouldn't decrease or increase drive performance but you might as well just use the second drive to Time Machine backup your photo drive IMO.
  5. wheezy thread starter macrumors 65816


    Apr 7, 2005
    Alpine, UT
    I already have Time Machine setup on my Main drive, and I don't think you can turn on two.

    Has anyone ever used the OS X Software RAID???
  6. aliot macrumors member

    Jun 19, 2008
    In fact,I have use a 4HD softraid0 for 8 month(4X 250G seagate 7200.10).I think it's reliable enough for normal use
  7. m1stake macrumors 68000

    Jan 17, 2008
    I haven't used it for a year or so, but it was perfectly reliable. And even if it did have an issue, you'd suffer no data loss because of the RAID1 mirroring configuration. Software fails -> no problem. Hardware fails -> no problem.

    Software RAID is kind of dumb IMO, some other people can point you in the direction of a RAID card that doesn't suck like Apple's option.
  8. wheezy thread starter macrumors 65816


    Apr 7, 2005
    Alpine, UT
    Awesome, an answer from someone doing it! That's what I'm looking for.

    I'm not going at a RAID for any mega-speed improvement, but rather the automatic backup of data, so even though the software RAID doesn't really match a hardware RAID, it's exactly what I'm looking for in this instance. I'm tired of external drives, so having everything internal is great.
  9. Umbongo macrumors 601


    Sep 14, 2006
    Just bare in mind a RAID setup isn't a backup system. It is a way of preventing data loss due to disk failure. If you value your data you will have both in place.
  10. UltraNEO* macrumors 601


    Jun 16, 2007

    Data is near enough always recoverable, no matter if the HD's have crashed or crash landed (black boxes) It'll just depends how much your willing to pay someone to do it. Having HD's arranged in any RAID format will make recovery slightly more complicated!! Data recovery companies make huge money on this...

    Software raid isn't fool proof, it'll only be as secure as your HD and bad programming can lead to errors been written on the drive. If you need speed and data redundancy, you might like to consider hardware raid, though that'll come at a cost since you'll need additional interface card and in some cases an external APS.
  11. sickmacdoc macrumors 68020


    Jun 14, 2008
    New Hampshire
    I totally agree there- the first time you inadvertently delete a file and find both your copies have been erased, or a write to disk goes bad and both copies are trash the difference will be painfully obvious! ;)
  12. MacsRgr8 macrumors 604


    Sep 8, 2002
    The Netherlands
    I use Apple's software RAID 1 (via Disk Utility) a lot when installing Xserves.

    Usually the (shared) data of such a server is stored on a HW RAID like the good ol' Xserve RAID, or the not-so-pretty-but-awesome-Promise.
    But I install the OS mostly on a soft-mirrored 2 x 80 GB internal S-ATA disks, and this approach serves me well. Apple Disk Utility gives you the very easy method of repairing this RAID, and it is a very cheap way to do it.

    There is a slight performance penalty in using a soft RAID 1, but it is only marginal, and the benefits of creating a cheap disk-fail-over outweighs the cons of experiencing very minor speed decrease. The real Need for Speed for your shared data is done by the external HW RAID 5 (or 6) anyway.

    BUT.. it is NOT a backup. If you delete data on a RAID 1 it is by definition removed from "both" disks. A RAID 1 is only there to have the reassurance of having 2 disks doing the job of one disk, to half the chance of disk failure resulting in data loss.
  13. Macinposh macrumors 6502a

    Jun 7, 2006
    A quickie: been running a software raid10 for 27 moths now,without any hickups(knocks wood).

    In the meanwhile i personally know 2 malfunctioned apples raid cards and read here about few.

    So in my books software ride is groovy,and bang-for-buck,it is the shitznizz.

    Obviously for archiving you need different stuff,but for the daily workflow it is nice.At least from my experience.
  14. wheezy thread starter macrumors 65816


    Apr 7, 2005
    Alpine, UT
    My main 'backup' wish was just having two copies in case the hard drive fails, right now if my external firewire 400 drive craps out on me I have nothing, so have a mirrored RAID would give me at least that assurance.
  15. elbirth macrumors 65816

    Jan 19, 2006
    North Carolina, US
    Just to chime in here with another experience...

    I've been using a mirrored RAID via Apple's software RAID in Disk Utility also on 2 1TB drives and it's been quite reliable. The RAID is solely for data storage and isn't something being accessed constantly, so I notice no performance issues.
    Last month I did have a problem where the drive in bay #2 became corrupt (it was one of the drives in the array) but the 2nd drive maintained its data fully intact with no issues as expected.
    This corruption issue turned out to be a problem with the bay itself because I replaced the drive and whatever drive I put in that particular bay would fail after a few days, so I had to take it in to Apple for repair. Regardless of the 1 drive continuously becoming corrupt, the mirrored drive held up like a champ and I'm quite happy with the setup.
    I also have Time Machine on a 1TB external drive backing up the drive for an additional layer of backup/protection, so it all works out well.
  16. sushi Moderator emeritus


    Jul 19, 2002
    My experience comes from Panther. I have not tried it with Tiger or Leopard. I am sure Apple has improved it over time. But based upon my very negative experience, I have never tried a software RAID again using Mac OS X.

    Personally, I believe that a hardware based RAID is better than a software based one.

    Using a RAID is not backing up your data.

    A RAID is to protect you against hardware (HD) failure.

    For photos, after taking pictures, I burn them to CD/DVD. That way I have a back up of the original files. Call it the negatives if you will.

    Personally, I backup weekly to an external hard drive using Carbon Copy Cloner (CCC). It works well and creates a bootable image.

    A mirrored HD is okay.

    However, I would recommend the following:

    - Burning your photos to CD/DVD when you take them.

    - Making routine backups of your mirrored drives using Carbon Copy Cloner (CCC) or SuperDuper.

    - Be sure to store a backup of your HD off site on a rotation basis.

    Then after importing, backup on a regular basis to an external HD.

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