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Thread: Change capacity of a RAID 0 Set

  1. #1
    Join Date
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    Default Change capacity of a RAID 0 Set

    I've got a two bay Burly enclosure that I initially set up with two 750 GB drives as a RAID 0 set. One of the drives failed and I replaced it with a 1 TB drive. There were no issues replacing the drive and using Disk Utility to rebuild the RAID set. As expected, the total capacity of the hard drive representing my RAID set was the same as the smaller drive - 698 GB.

    I've subsequently upgraded the last of the original drives with another 1 TB drive. Again, there were no issues replacing the drive and using Disk Utility to rebuild the RAID set. However, the total capacity of the hard drive representing my RAID set has not changed. It's still 698 GB, but the two slices are both 932 GB.

    How do change or update the capacity to reflect the additional 234 GB of space?

    Thank you in advance for the advice!

  2. #2
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    Delete the RAID. Then select the drive model number itself and erase it.

    Any time you create a RAID make sure you select the drive, not the volume under it. So if you erase the top drive ands name it 'Top'. Then want to RAID it, select the line above Top which has the hard drive icon and the model number for your RAID.

    I'll bet the new small sized RAID had the lower formatted volume selected during the create process. Easy to do.

    Rick
    molṑn labe'
    "I am a mortal enemy to arbitrary government and unlimited power. I am naturally very jealous for the rights and liberties of my country, and the least encroachment of those invaluable privileges is apt to make my blood boil."
--Ben Franklin

  3. #3
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    Quote Originally Posted by ricks View Post
    Delete the RAID. Then select the drive model number itself and erase it.

    Any time you create a RAID make sure you select the drive, not the volume under it. So if you erase the top drive ands name it 'Top'. Then want to RAID it, select the line above Top which has the hard drive icon and the model number for your RAID.

    I'll bet the new small sized RAID had the lower formatted volume selected during the create process. Easy to do.

    Rick
    I think I understand your instructions, but want to confirm because I don't want to loose the any data in the mirrored set. The RAID set is configured as the target drive for my Time Machine backups and I don't want to loose the Time Machine database & backups.

    Will following your instructions erase data on either or both of the two drives?

  4. #4
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    It will ALWAYS erase all the data to reformat it.

    Now I understand why you didn't gain any capacity, you are in a mirror, so you didn't build a new RAID, you replaced one drive in a mirror set. It cannot add in the increased capacity without a reformat, which deletes the data - well, actually deletes the index to the data.

    I would recommend you reconsider your entire backup strategy. I see potential issue from both Time Machine and from Mirrors. Fine as long as you know the weakness of each, but you must account for every type of configuration's weaknesses as well as the strengths, when you make a backup plan.

    Time Machine - works ok as long as you erase the drive and start over on a regular basis. TM gets bigger and more complex every day, eventually it inevitably gets corrupted and useless. We did testing here on 11 computers and we failed every Time Machine backup, on every computer, within 10 months. As long as you erase the drive completely and start over on a regular basis, (maybe 3 months? depends on how dynamic and active the database is) TM works pretty well.

    Understand that the weakness of Time Machine is that it isn't making a copy, it is making a proprietary database out of your data. You cannot use the data in the form that it is stored in. Instead, the TM application has to 'recover' the data for you, a MUCH more complex activity. If anything corrupts the permissions, time stamps, index or the data itself, TM quickly gets to where it is useless, corrupted and not functional.

    Next is mirrors. I cannot imagine a benefit from using mirrors on a desktop computer. They are almost completely ineffective in providing any added data security - they are designed to provide uptime on a server in the event of a minor drive failure situation. They are complex, which adds in the problem of the mirror itself failing. And they make many types of problems worse - ie, any damage done the data on one side of the mirror is instantly duplicated to the other side of the mirror.

    I would MUCH rather have drive 1 backed up to drive 2 using a backup application than have them in a mirror. That way drive 2 is actually a backup. Any catastrophic event and at least the second drive is not directly attached and part of the problem.

    Rick
    molṑn labe'
    "I am a mortal enemy to arbitrary government and unlimited power. I am naturally very jealous for the rights and liberties of my country, and the least encroachment of those invaluable privileges is apt to make my blood boil."
--Ben Franklin

  5. #5
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    on the landline, Mr. Smith
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    Default

    FYI:

    RAID 0 = Stripe
    RAID 1 = Mirror

    (easy to remember tip: RAID 0 has zero redundancy)

    So everybody is on the same RAID page.
    "Imagine if every Thursday your shoes exploded if you tied them the usual way. This happens to us all the time with computers, and nobody thinks of complaining." -- Jef Raskin

  6. #6
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    Talking

    Big 10-4 on that Rick! ...... preach it ...... brother!

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