OMV5 Mirror Raid Config

  • votdev I believe there is an issue with the creation and maintenance of a Raid 1 Mirror which I can replicate in a VM at present I am trying to assist the OP of this thread


    I have an OMV5 VM which I use for testing various scenarios and I can actually replicate what the OP has done, I have 3 small virtual data drives in the VM.


    Raid Management -> Create -> the dialog is fine, and all three drives are displayed, if I select Mirror with all three drives selected the Raid is created appears as clean but the size is correct for two drives, but devices used displays three, if I remove a drive from the array it appears as clean/degraded but shows two devices.


    Likewise if I create a Mirror with two drives it appears OK, but I click grow or recover from the menu and select the third drive, this gets added, the size remains the same but the devices now show three.


    Granted I have not created a file system but the Mirror option should only allow the user to select two drives only from the list displayed, a user should also not be able to grow a clean mirror.

  • A mirror raid means all drives in the array are the same. So, a three drive array is the same size as a two drive array which is the same size as a single drive.


    A three drive mirror gives you double redundancy versus single drive redundancy of a two drive array. It is also faster for reads in some situations.

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  • A mirror raid means all drives in the array are the same. So, a three drive array is the same size as a two drive array which is the same size as a single drive.

    I agree with, but with regard to the OP from the thread he has obviously added 2x4TB drives to his 2x1TB array hence he's gained no additional space but for the average end user this becomes confusing.

    A three drive mirror gives you double redundancy versus single drive redundancy of a two drive array

    :/ I have just tested that on the VM if I remove one drive via Raid Management I cannot remove another and the Raid remains as clean/degraded.


    But my other point was that a user can add a drive to an existing Raid 1 without understanding what they are doing, imho that should be disabled.

  • I agree with, but with regard to the OP from the thread he has obviously added 2x4TB drives to his 2x1TB array hence he's gained no additional space but for the average end user this becomes confusing.

    But that is how it works. Not sure what to tell a user. mdadm only uses the space of the smallest drive. So, that array should only have 1 TB of space.

    I have just tested that on the VM if I remove one drive via Raid Management I cannot remove another and the Raid remains as clean/degraded.

    It should be degraded since you removed a drive. I think it is good that the web interface doesn't let you remove a drive from a degraded array even if the array supports it.


    But my other point was that a user can add a drive to an existing Raid 1 without understanding what they are doing, imho that should be disabled.

    I can't tell Volker what to do but users shouldn't use raid if they don't understand how it works.

    omv 5.5.12 usul | 64 bit | 5.4 proxmox kernel | omvextrasorg 5.4.2
    omv-extras.org plugins source code and issue tracker - github


    Please read this before posting a question.
    Please don't PM for support... Too many PMs!

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