RAID set up help

Discussion in 'Mac Pro' started by Fiercehairdo, May 15, 2009.

  1. Fiercehairdo macrumors member

    Joined:
    Dec 19, 2007
    #1
    Hi,

    I'm buying a new mac pro and am trying to figure out the the configuration of Hard drives.

    All these options are in addition to the already existing internal drive which I would leave as is.

    I would like 2 internal 1 TB hard drives and 2 external 1 TB hard drives. With the 2 internals set up as RAID 0 and the externals a RAID 1 (mirror) of the internals.
    Will this work?

    An alternative option:
    3 Int 1TB HDs and 1 ext 1 TB HD. Can I get this set up as a RAID 0+1? With 2 internals RAID 0 and one internal and one external mirroring in RAID 1 the first two internals?

    Also, this will all be software RAID. Is that a safe, reliable option? Hardware RAID seems so expensive.

    Many thanks.
     
  2. nanofrog macrumors G4

    Joined:
    May 6, 2008
    #2
    Software RAID is fine for 0/1/10, which OS X can do. For RAID 10, you're better off sticking with all internal drives to avoid any throughput loss on an external drive (i.e. 3 SATA + 1 FW800 or USB).

    If you need a 5th HDD, you can place it in the empty optical bay with a simple 3.5" to 5.25" adapter bracket, and a SATA cable. Really easy to install, and not expensive either. :)

    Is there a particular reason for not filling the HDD bays?
     
  3. Fiercehairdo thread starter macrumors member

    Joined:
    Dec 19, 2007
    #3
    I didn't realise I could fit a 5th HDD internally. Any links on where to get the bracket and how to install it...?

    On my first option of 2 internals and 2 externals I had assumed that mirroring the internals would be easier to two externals rather than mirroring to one internal and one external. But I don't know if that is a mistaken assumption. (the main boot hard drive wont be part of the RAID).
     
  4. nanofrog macrumors G4

    Joined:
    May 6, 2008
    #4
    Here's the bracket. You can find them for less on eBay though. ;) Installation is just a few screws. :D Plug in the cable to both the drive and logic board, and presto..DONE. :D :p

    Super easy. :)

    As for the arrays, create two mirrors first. Then stripe the two together. (Hence 1+0 or 10). That's it. :D Initialization might take a few hours each mirror, and you can create the mirrors simultaneously to save some time. ;)

    Put the 5th HDD in the optical bay, and use that one as the OS drive. Assuming you wish to use the drive sent with the system, just relocate it. :) That way, you can retain the sleds for the 10 array. ;)
     
  5. Tesselator macrumors 601

    Tesselator

    Joined:
    Jan 9, 2008
    Location:
    Japan
    #5
    My only question is what's your interest/intent in mirroring?

    But yeah, software RAID is safe, reliable and sane. It's not as "safe" as some hardware RAID solutions but the difference is usually splitting hairs - especially for a desktop configuration like you're attempting here.

    If you understand what mirroring actually accomplishes and you want that then a hardware solution which supports RAID level 5 might indeed be a consideration. RAID 5 is greatly superior to RAID 10.
     
  6. nanofrog macrumors G4

    Joined:
    May 6, 2008
    #6
    From what I gather, it's due to the fact the OP wants to avoid the expense of a hardware controller, and is the best balance of speed/redundancy OS X offers. :D
     
  7. Tesselator macrumors 601

    Tesselator

    Joined:
    Jan 9, 2008
    Location:
    Japan
    #7
    Yeah, if redundancy is even needed. But let's see what he comes up with. :) Of course you probably already know by now that I think redundancy in drives is about as useful to the typical user as redundancy in displays. And displays probably break more often. :p So it's like recommending to run two monitors in mirror mode all the time just in case one breaks. :p Sure it might be useful if one ever breaks but no one does it cuz it's fairly ridiculous. This is my opinion of RAID 1. :D
     
  8. Fiercehairdo thread starter macrumors member

    Joined:
    Dec 19, 2007
    #8
    I wanted mirroring simply to safeguard the data on the striped hard drives. I figure that if I have 2 drives striped amounting to 2TB of info then that's a lot of data to lose if something goes wrong. Do you think its overkill? (I've also been advised to back up on external drives, kept off site, but it does start to feel a little like overkill - 6TB space to safe guard just 2 TB of usable space!).

    RAID 5 was my preferred choice but it seems very expensive since I'd need a RAID card. Especially if I can get an alternative RAID option free of charge in OSX.
     
  9. Fiercehairdo thread starter macrumors member

    Joined:
    Dec 19, 2007
    #9
    I know what you mean. I've had a G5 Power Mac for about 5 years now and have worked with no redundancy and no real back up and have not had a single problem with losing data (Obviously that is tempting fate and the machine will probably explode in the next 10 minutes!). I now have a 'back up' on Time Machine of everything, but how common is hard drive failure? People talk like it happens all the time.
     
  10. matperk macrumors 6502

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    May 6, 2004
    Location:
    Milwaukee, Wisconsin
    #10
    I thought OS X can do software RAID 5?
     
  11. Fiercehairdo thread starter macrumors member

    Joined:
    Dec 19, 2007
    #11
    I don't think so. Only Hardware RAID 5 with a RAID card.

    OSX Software RAID is limited to just RAID 0, RAID 1 or JBOD
     
  12. Tesselator macrumors 601

    Tesselator

    Joined:
    Jan 9, 2008
    Location:
    Japan
    #12
    Actually I think that's the norm - so it's not tempting fate at all.

    I dunno what the actual numbers are or even if such numbers are available but I would guess it's like for 1 to 3 year owners the chances are in the hundreds of thousands like maybe it would break down like:
    1 month ~ 6 months 1:1,000
    6 months ~ 3 years = 1:100,000
    4 years ~ 5 years = 1:10,000
    5 years and after = 1:1,000​

    Or probably something very very close to that - for the past 5 or 6 years anyway. 15 years ago I bet you could easily take a zero off the end of all of those. And I think the modern day paranoia stems from those older statistics.

    EDIT:
    That's for disk failure itself and doesn't include a PSU going bananas, someone dropping it, running then on bouncy or wobbly surfaces, running them for extended periods at or above their maximum temperature rating, lightening strikes, or other such stuff.
     
  13. nanofrog macrumors G4

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    May 6, 2008
    #13
    No RAID 5 in OS X, but it can do 10/01. :)
     
  14. Tesselator macrumors 601

    Tesselator

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    Jan 9, 2008
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    #14
    Yeah, I wish there was RAID 5 in OS X tho! That would be sweet!
     
  15. Mac Husky macrumors regular

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    Mar 28, 2009
    Location:
    Bavaria, Germany
    #15
    And that´s not the worst idea to handle the set up as it could happen all the time, is it?!
    You must not handle it as it happens all the time, but as it could happen every time.
    When it hits you it´s to late to think about it. Better be prepared.
     
  16. Tesselator macrumors 601

    Tesselator

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    Jan 9, 2008
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    Japan
    #16
    It only needs a backup. RAID 1 isn't of much use IMO. A software backup will protect you in all cases. RAID 1 will only save you in some very arcane circumstances.
     
  17. nanofrog macrumors G4

    Joined:
    May 6, 2008
    #17
    It's useful for high availability (uptime). Useful for servers, but not needed for most systems.

    So long as there's a proper backup, replacing a dead drive and restoring the data isn't that difficult. ;) :D
     
  18. wheezy macrumors 65816

    wheezy

    Joined:
    Apr 7, 2005
    Location:
    Alpine, UT
    #18
    Here's what I've got going right now:

    2x1TB RAID0:
    64GB OS
    1.6TB Files, Files and more Files
    1TB Time Machine:
    20GB Scratch for PS
    980GB for Time Machine and Aperture Vault 1
    500GB
    Aperture Vault 2

    I initially had a RAID1 setup for my pictures, but it really is pointless. Two drives taking up two bays but equaling only 1 drive. Now, having the OS and files on a RAID0 my system just screams and I have plenty of space for everything on my 2TB RAID, Time Machine is only half full, and having a 2nd Aperture Vault just makes me happy.

    XBENCH drive results

    2TB RAID0
    Sequential
    Uncached Write - 276MB/sec (4K Blocks)
    Uncached Write - 257MB/sec (256K)
    Uncached Read - 18.48MB/sec (4K)
    Uncached Read - 212MB/sec (256K)

    Random
    Uncached Write - 6.54 4K
    Uncached Write - 220 256K
    Uncached Read - 1.32 4K
    Uncached Read - 52.48 256K

    PS - All drives are Samsung F1 32MB Cache 1TB 7200 Drives
     
  19. Tesselator macrumors 601

    Tesselator

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    Jan 9, 2008
    Location:
    Japan
    #19
    Yup, I agree. I think RAID 5 is better for that tho. I mean if you're involved with something like that you've probably got the means and need for a RAID card anyway. :cool:
     
  20. nanofrog macrumors G4

    Joined:
    May 6, 2008
    #20
    Assuming they've the budget. :eek: ;)

    A 1U rack and 3 HDD's at best (RAID 1 + backup), on a board that doesn't support RAID 5. A server on the super cheap. :D :p
     

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