Moving to a larger RAID 1 array

1. offizieller Beitrag

    Hello All,


    I currently have a 2TB RAID 1 array on a HP Microserver but one of the drives is generating messages like:



    which it seems, after research, is a "bad thing" :)


    So I have ordered 2 3TB WD Red drives but I need advice on how to migrate to a larger RAID 1 array or should I consider another arrangement involving the two drives? I have backups to external USB and the data on the drives is not changing often, just new files being added. The other 2 bays are in use with 2 non-RAID 1TB drives but I could remove these temporarily to create the new array, is this the best way?


    or can I combine the surviving 2TB drive with the 2 new 3TB ones to create a larger array and remove one of the 1TB drives? It is all too confusing, so many options!


    Advice much appreciated ..

    • Offizieller Beitrag

    You can remove one of the working ones (non-raid1) and insert a new red. With one new red you can create a raid1 degraded array, that means it will be missing one drive. Copy the data from the old raid1 to the new one. After that remove the old array, and insert the second red and add it to the new raid1.Don't forget to disconnect the old shares from the old array, otherwise you're going to have a lot of orphans shares later.

    Many thanks for the reply! I do have a lot of shares though :( Am I able to remove the bad disk, add a new red and then "grow" the existing array to 3TB. When this is done, replace the remaining 2TB disk. Does this make sense raid-wise?

    Am i best to do this via the OMV GUI or from the command line? I assume once I restart with the degraded array, I add the new unformatted red disk to the array and then just hit "Grow", seems too easy!

    • Offizieller Beitrag

    There is a few things....


    1) when you add a disk different size to an array (raid1) the total size will be the smallest drive.


    2) To mark a disk as failed and remove, this is only done in the CLI with mdadm


    3) After you add the first red 3TB, you need to wait until the resync finishes. That means all data from 2TB (good one) mirrored to the new 3TB one. This can take some time (5-8 hours maybe more). You filesystem will still be 2TB no matter what.


    4) once the sync is finished you can go and remove the 2TB with CLI again, and then add the new 3TB. Syncing process starts again (long time). from there you will need to expand the FS to 3TB.


    You can always practice this in a virtual machine before committing to the real metal, take a look at my signature


    Another approach will be to remove one of the 1TB, so you can add the 2x3TB to the old raid1 (degraded one missing/removed) wait the resync, and when is finished remove the old 2TB, expand FS again


    About GUI, you can grow a raid and you can expand the FS. You cannot construct a degraded array or mark drives as failed or remove them


    Edit: The grow raid option is not for RAID1

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