Trying to do a raid 5 of 6x 8TB drives and it wont let me?

Discussion in 'SSDs & Data Storage' started by IceDigger, Mar 23, 2019.

  1. IceDigger

    IceDigger [H]ardForum Junkie

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    I have a media server with 4x 8tb drives in raid 5.

    I finally bought 2 more 8tb drives to make it bigger.

    All 6 drives are 8tb sas drives.

    The avago sas controller software will not let me combine all 6 drives though.

    It is stating that the 2 new drives are 7.154TB and the 4 previous ones are 7.277TB.

    They are all HGST drives except the 2 newer ones are newer models.
    Any help is appreciated.

    sas.png
     
  2. Spartacus09

    Spartacus09 Gawd

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    Unfortunatly due to the new drives being slightly smaller they will not be able to add them to the array. You need the same size or larger, even if only by a few humdred megs.
     
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  3. IceDigger

    IceDigger [H]ardForum Junkie

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    Thats what I was hoping wasn't the problem.

    Thanks.
     
  4. westrock2000

    westrock2000 [H]ardForum Junkie

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    8TB*

    * Your results may vary.
     
  5. ryan_975

    ryan_975 [H]ardForum Junkie

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    Delete the current array.
    Build a new one.
    Restore the data from backup.
     
  6. IceDigger

    IceDigger [H]ardForum Junkie

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    That wont work. Tried it anyway.

    Apparently I'm finding out all 8TB drives are not the same size....
     
  7. ryan_975

    ryan_975 [H]ardForum Junkie

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    You might be able to change the reported drive sizes of the larger drives to match the smaller ones using the manufacturer's diagnostic tool.
     
  8. Blue Fox

    Blue Fox [H]ardForum Junkie

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    That won't work. You're looking at data loss if anything is stored at the end of each drive and RAID metadata might be there too. A lot of RAID cards will actually let you round down to the nearest 1GB or 10GB to alleviate this exact problem.
     
  9. ryan_975

    ryan_975 [H]ardForum Junkie

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    Oh for sure. I wasnt meaning to do that with drives in an existing array. But If he were building the array from scratch (as it sounds like he's doing from his last post), the RAID controller wouldn't know there was anything beyond the drive's highest reported sector.
     
  10. Dead Parrot

    Dead Parrot 2[H]4U

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    When you rebuilt the array did you start with the new smaller drives first? If the array accepts the small drives as the norm, then the older larger drives should be addable.

    If that doesn't work, is there some manufacturer's utility to adjust the size of the older drives to match that of the newer ones? Might be worth a call to the drive's tech support folks. Can't be the first time this has popped up.
     
  11. mwroobel

    mwroobel [H]ardness Supreme

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    If you were using an Areca series card you would be fine, there is a feature called “Disk Capacity Truncation Mode” which negates this problem by making all the drives the same size to the controller using the lowest common denominator in size. It would only use the amount of space of the smallest drive allowing you to use all your drives in an array. You can see if your particular controller has a similar function. In any case, you would have to delete you array, enable the feature and recreate the array.
     
  12. likeman

    likeman Gawd

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    Seems his software is not agreeing with him having different size hdds on raid 5 array (be better if you use raid 6 so at least 2 disks fail won't take out your array strongly recommended raid 6 or Windows new storage spaces +2 redundancy and it doesn't care about different disk sizes)

    As these are sas drives you should be able to set there LBA size via the drives tool so every drive has same LBA size
     
  13. IceDigger

    IceDigger [H]ardForum Junkie

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    Not sure what to do yet. I have a lot of linux isos on that array. Takes forever to back them up... ;)
     
  14. geok1ng

    geok1ng 2[H]4U

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    The more drives you have, more risky RAID 5 becomes.
    If you think that back up takes too much time, there is zero chance you can endure the wait for a RAID 5 rebuild when one of your disks die.
    Take this problem as the universe warning you that it is time to move to RAID 10.
     
  15. EmualDave2k12

    EmualDave2k12 n00b

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    or maybe have a look at UnRaid, this is what I am planning for my media server.
     
  16. Aluminum

    Aluminum Gawd

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    On the plus side, this is saving you from the mistake of doing another large drive RAID5 array.
     
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  17. drescherjm

    drescherjm [H]ardForum Junkie

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    I say use snapRAID instead with individual disks. Use 2 parity disks and make them external drives. You only need them when you sync, scrub or need to recover (from corruption or you want to undelete a file)
     
  18. Joust

    Joust 2[H]4U

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    Point of interest: this is why I used all matched drives. Exactly this. Luck.