Is it true any Mac Pro can do software RAID 0?

Discussion in 'Mac Basics and Help' started by yalag, Jun 26, 2008.

  1. yalag macrumors 65816

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    Nov 18, 2007
    #1
    I dont know why I never came across this, but is it true that any Mac Pro (or just macs in general??) can do software RAID 0 if you have two of the identical hard drives? Basically the OS handles everything and no special hardware or card is needed?

    If true, what would be the reason so little people do it for faster disk access??
     
  2. Spanky Deluxe macrumors 601

    Spanky Deluxe

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    #2
    Yes you can: http://www.barefeats.com/quad07.html (halfway down the page)

    As to why people don't do it more... well the extra performance for the cost and loss of hard drive space isn't really worth it for most people.
     
  3. merl1n macrumors 65816

    merl1n

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    #3
    Yes, all current (and older) macs can do it.

    The reason most folks don't use RAID 0 is that:

    1. If you lose one disk of the RAID set, you lose the entire RAID set.
    2. The RAID is done by software, unless you have an actual Hardware RAID controller. Thus, no speed advantage.
     
  4. anim8or macrumors 65816

    anim8or

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    #4
    Point one is kinda obsolete now that Time machine is in place.... correct??
     
  5. merl1n macrumors 65816

    merl1n

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    #5
    Only if he uses it and has another drive for it.
     
  6. QuantumLo0p macrumors 6502a

    QuantumLo0p

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    #6

    Anyone who is at risk to lose valuable data should have a backup and restore strategy, raid or not. People who have never backed up anything in their lives really should experience a huge, devastating loss to appreciate a good backup. Life favors the prepared!

    There are speed advantages to software raid, although not as large as hardware raid.

    Some people simply throw any disks they have into a pool to have single, large disk. Not raid, just a collection of different disks acting as a single, large disk. Again, backups are always a great idea.
     
  7. merl1n macrumors 65816

    merl1n

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    #7
    Only if the disks are on separate buses and they have large "write caches" onboard. I don't own a MP so I'm not sure if the internal drives are daisy chained using the same bus or there are two internal/separate I/O buses.

    I don't see (if they are daisy chained) how there could be a speed increase as you are now adding another layer of software on it.

    The only advantage I can see is if you want a "larger volume". RAID 0 can double the size of a single drive by combining two identical drives into one large drive.
     
  8. ChrisA macrumors G4

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    Jan 5, 2006
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    Redondo Beach, California
    #8
    Time machine and raid-0 are not a good match.

    First off "RAID 0" really means "zero RAID" and is "no raid". Raid zero combines two drives to give you one larger drive. It can sometimes be faster because (even in software) you gain some bandwidth and can do reads and writes in parallel. But the "R" in Raid stands for "Redundant" and in raid-0 you give up the redundant thing.

    Now with Time Machine you have a problem. The TM dive needs to be LARGER then the drive(s) that are being backed up. If you are trying to back up a raid system your TM drive will likely also need to be a raid system that is even larger. It would be really stupid to use raid-0 for the TM drive. Mac OS X software can only handle raid-0 and raid-1 (mirror) You need a hardware raid system for TM.

    So if you have the hardware raid for TM why not also use hardware raid for the data?

    OK there is one case where you don't need TM, if the raid-0 system is only used for video scrach files or a photoshop scratch disk then this data does not need to be backed up
     
  9. ChrisA macrumors G4

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    Jan 5, 2006
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    Redondo Beach, California
    #9
    The Mac Pro uses SATA drives. Each SATA drive has it's own cable.

    But even if the drives were the old IDE kind and shared a buss the buss speed so much, much faster then the sustained IO rate of the disk drive. So each drive on the bus uses only a fraction of the bus' available bandwidth. So raid-0 can be fast even if two IDE drives share an IDC controller. But the MP uses SATA.
     
  10. Julien macrumors G3

    Julien

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    Jun 30, 2007
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    Atlanta
    #10
    Not true, I have a Mac Pro with 2-750GB HD's as a software RAID-0 1.5TB drive and 2-1TB HD's as a software RAID-0 2TB Time Machine.
     
  11. keltorsori macrumors regular

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    Jul 24, 2002
    #11
    Any Mac can do software RAID 1 or 0 using disk utility to setup the RAID.
     

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