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Thread: Stripe & Mirror Combo

  1. #1
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    Hello All,

    Please can you advise the best means of accomplishing the following:
    I've got 2 x 9GB - Striped as a boot volume, working OK for the last two years. I now want to mirror this and have got an 18GB external Hard Drive, but I cannot select the striped partition as the source for the mirror. Am I attempting the impossible???
    Thanks for your advice

  2. #2
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    That can only be accomplished by hardware raid solutions. I don't know if there is any avaiable on the Mac side.

    j

  3. #3
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    Taken from the Gurus RAID FAQ:

    RAID 0/1, combining the best features of RAID 0 and RAID 1, involves the mirroring of a striped volume, yielding the best compromise in terms of performance with data redundancy. An example would be 14 drives striped as a single HFS+ RAID 0 volume, then mirrored, requiring a total of 28 drives to yield the capacity of fourteen drives. RAID 0/1 delivers the best combination of performance and data security theoretically attainable. Not yet feasible on the Macintosh using software, but forthcoming from SoftRAID LLC in a future update to SoftRAID.

    k

  4. #4
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    Of course stripping 14 drives only increase your potential failure rate 14X... sure Seagate makes GREAT DRIVES and I'm sure you are just using 14 as a number, to show the potential, but with 73GB drives out now and 180GB drives on the horizon - 14 is a bit much. I would think the practical limit is 8 stripped drives + 8 more for mirroring. Of course 14 would fill an UltraWide channel nicely!

    Then again, its much safter to have back something up to a drive you can remove and store saftely - like FIREWIRE.

    ------------------
    Have fun storming the castle!

  5. #5
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    Pendragon,
    Just a note on your point. Personally, for a FireWire drive to be a backup, I am looking for a native IEEE-1394 drive. Not an ATA in a different shell. Most ATA drives come with 1 or 2 year warranties. A lot of good a backup is if it is more likely to fail in a situation than your primary host. I can't wait til we see native FW drives...then it'll be perfect for that. For now, I am waiting for SoftRAID to support RAID 0/1.

  6. #6
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    SoftRAID just implemented RAID 1 over FireWire with the release of VST's proprietary FireRAID.

    Now would be the logical time for them to turn to providing at least RAID 0 and RAID 1 under OSX.

    I suspect RAID 0/1 won't be seen using software for awhile yet, depending on how long OSX-compatibility requires.

    of course, I am not Mark James, and do not speak for SoftRAID. Maybe we should invite him here to comment definitively?


  7. #7
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    Bubba - no technology will let you do waht you want, even hardware. RAID 0+1 in hardware requires 4 identical drives.

    When we do 0+1, we MAY allow some weird things like you intend, but I am not sure, as it makes a very complicated recovery process, and whiloe it is technically achievable, it may require a 2000 page manual to describe how it works!

    We are woking on RAID for OS X, though. It is going slow, as the driver kits from Apple, while mostly finished, are not totally complete, from our perspective.

    thanks

  8. #8
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    thanks, mark!

    always a pleasure to hear from you!


  9. #9
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    Thanks for your help guys. I guess I'll be buying another new drive.
    Delighted to hear about your progress with softraid for osx.

    Ta

  10. #10
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    Dogstar,

    Most of the Firewire-ATA/IDE drives I've seen are guaranteed for 3 years. You only need to connect the FW drive for backups - so it could actually last very long. Of course CD-r/w are a good way to back things up too... probably both FW and CD-r/w.

    SoftRAID for X!

    MacOS X uses HFS+ and SoftRAID-0 volumes seem to act like single HFS+ drives, except they are faster...

  11. #11
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    Dogstarman,

    re:
    "Just a note on your point. Personally, for a FireWire drive to be a backup, I am looking for a native IEEE-1394 drive. Not an ATA in a different shell. Most ATA drives come with 1 or 2 year warranties. A lot of good a backup is if it is more likely to fail in a situation than your primary host. I can't wait til we see native FW drives...then it'll be perfect for that. For now, I am waiting for SoftRAID to support RAID 0/1.
    "



    If you want the most reliable firewire drive setup, setup a Seagate drive in an external case connected to a SCSI-->Firewire converter with Granite Digital cables. Can't get any better than that.

    j.

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