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Thread: Software Raid 1 pitfalls?

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    Software Raid 1 pitfalls?

    I am thinking of using disc utility to create a RAID 1 set with two external drives.

    What happens if one drive fails? Can I simply mount the other drive and read the information? Or is that drive always and forever confined to the RAID set? IOW, I would have to rebuild the mirror no matter what?

    Similarly, what if the boot drive goes T-U? will the RAID pair be recognized by any computer it is connected to?

    Pretty basic questions. Apologies.

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    Re: Software Raid 1 pitfalls?

    With a raid and a reasonable driver (speaking from a Mac point of view)
    If one of the pair fails, then the mirror is broken and the remaining drive can be used. At that point a replacement drive can be added and the raid set re-built. I like SoftRaid since it is a little more flexible than the OsX driver.
    If the boot drive goes T-U, just replace it.
    I have a large raid-0 set and boot from one or more boot drives. It works fine as long as the driver is installed on all boot drives you have.
    -bob

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    Re: Software Raid 1 pitfalls?

    so when you say driver from a mac OS pov you mean either softraid or apple disc utility raid?

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    Re: Software Raid 1 pitfalls?

    Yes, that is what I mean.
    Don't try booting an OS9 system, you will be very disappointed.
    When preparing the alternate boot drive (you keep a spare on hand don't you?) make sure that you pre-install the appropriate driver. One good way is to periodically clone your boot drive as long as you are sure that it is stable.
    -bob

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    Re: Software Raid 1 pitfalls?

    the whole picture is I use SuperDuper to clone everything right now. Which is great, but if there is a failure it is only backed up to the last point of cloning.

    I was considering moving my main photo drive to a mirrored raid, which would give me instant redundancy. speed in not an issue.

    I could then clone a third drive as a further backup on a scheduled basis. three copies.

    yes, I have a spare boot clone, had to run off of it for a week once while the tower was in getting fixed.

    Superdupered it back to the tower once the repair was done and everything was seamless!

    have to love bootable clones in Mac OS X!

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    Re: Software Raid 1 pitfalls?

    further question- if in converting a drive "photo" to a raid mirror set, can the data be retained or do I have to create the set clean, and then copy the data to it afterwards?

    or look at it the other way, I have "photo" and "photo mirror" right now which are clones. Can I just create the raid mirror with those two drives as is and retain the data?

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    Re: Software Raid 1 pitfalls?

    My setup is a little more complicated.
    I use six 1TB drives installed in the tower and an external Drobo.
    I have four of the six drives partitioned into scratch, main, and archive all Raid-0
    The remaining two drives are also Raid-0 and partitioned into a boot and a time-machine partition.
    An external boot drive is present and cloned periodically from my boot partition.
    TM backs up main.
    Main and archive are backed up nightly to the drobo
    Archive is also backed up to external drives, organized by year, and placed in the vault.
    Raw images are also burned to dvd, organized by year, and also placed in the vault.
    -bob

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    Re: Software Raid 1 pitfalls?

    phew! thanks for the reply.

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    Re: Software Raid 1 pitfalls?

    Quote Originally Posted by robertwright View Post
    further question- if in converting a drive "photo" to a raid mirror set, can the data be retained or do I have to create the set clean, and then copy the data to it afterwards?

    or look at it the other way, I have "photo" and "photo mirror" right now which are clones. Can I just create the raid mirror with those two drives as is and retain the data?
    According to the documentation that ought to work, but I am a bit more cautious. I would start fresh with two new identical drives.
    Make the raid-set then copy the data to the new raid set.
    I hate the idea of having my only two copies involved in a low level driver function.
    When things go bad, they go very bad
    -bob

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    Re: Software Raid 1 pitfalls?

    agreed. I would have a third copy before trying that one!

    really this is trying to extract maximum value out of cheap lacie externals. got lots of them.

    I'm thinking more now just to get a cheap lacie hardware tooBig raid, 1TB, plug and play.

    keep the clones as well offline.

    the price of all this stuff has come down so much that I think redundancy is easier than elegance.

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    Re: Software Raid 1 pitfalls?

    ABSOLUTELY right on!
    Disk is almost free.
    -bob

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