RAID5 with Luks, Can I still reconstruct the RAID5 if one drive fails?

  • Hi,

    I created a RAID 5 array with the RAID Management tab from OMV 5, then I encrypted that array and then I created the biggest filesystem possible. If I reboot OMV, that filesystem is only available when I decrypt the array.


    My problem is I just realized by trying different things with Virtualbox (removing one disk from the array and adding a new empty one) that if I lose one disk I can't rebuild the RAID array with a new disk (the Recover button is greyed and my array disappeared), am I wrong? Is it because I encrypted the array afterward? I thought once the array is created the RAID 5 would just act on encrypted data like it would on unencrypted and it would not matter.


    I don't have enough space to backup what's on that array elsewhere, so before reinstalling OMV (one my docker container don't work as it should anymore and I don't know enough to fix it) on my system drive I wanted to try in a virtual machine and now I'm worried if one drive fails I lose all my data.

  • I've never used encryption so I can't comment on that, but best guess would be you will have to unlock the array before replacing a drive.


    As a pointer mdadm, OMV's software raid is not hot swappable like hardware raid, if a drive has died it gets removed from the array and it's displayed as clean/degraded, add a drive, wipe it, then recover on raid management.


    Can you simulate a drive failure -> No, if you 'pull' a drive from an array the raid become inactive.

    Raid is not a backup! Would you go skydiving without a parachute?

  • I actually just tried in a VM the same thing without encryption and the result is the same, so it's probably totally unrelated to encryption.

    As a pointer mdadm, OMV's software raid is not hot swappable like hardware raid, if a drive has died it gets removed from the array and it's displayed as clean/degraded, add a drive, wipe it, then recover on raid management.


    Can you simulate a drive failure -> No, if you 'pull' a drive from an array the raid become inactive.

    What I don't understand is, let's imagine one of the dive is completly ruined when the server is off, to the point where it is not recognised in the bios and all the other drives are OK. How is it different from pulling out a drive?

    I'm supposed to be able to rebuild the array with another drive. The array become inactive, it makes sense, I suppose that's why it no longer appear in the GUI.

    When I tried to search more details with the command line, I was able to confirm the array is indeed inactive, but it is recognised as a 4 disks array instead of 5 and RAID0 instead of RAID5 :

    "

    Raid Level : raid0

    Total Devices : 4"

    I'm kind of lost.

  • What I don't understand is, let's imagine one of the dive is completly ruined when the server is off, to the point where it is not recognised in the bios and all the other drives are OK. How is it different from pulling out a drive

    It's not, but the likelihood of that happening is somewhat remote.


    I suppose that's why it no longer appear in the GUI.

    Inactive doesn't mean the raid is lost.

    I was able to confirm the array is indeed inactive, but it is recognised as a 4 disks array instead of 5 and RAID0 instead of RAID5 :

    Mdadm can't magically change how a raid is set up, what hardware is this running on.


    Look at this the output from each will give information on the raid.

    Raid is not a backup! Would you go skydiving without a parachute?

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