Odd behavior with multiple insances of UnionFS with same drives

  • I'm trying to create two different instances of MergerFS on the same drive pool to have different policies and options, and while I'm able to create the two instances when I try to create a shared folder both instances show up as the same device, see attached images.

  • By ambiguous, I mean that the target branches are the same. The names of the pools being different doesn't change that.


    Let's see what @trapexit sez.

    --
    Google is your friend and Bob's your uncle!


    OMV AMD64 5.x on ASRock Rack C2550D4I C0 Stepping - 16GB ECC - Silverstone DS380 + Silverstone DS380 DAS Box.

  • I have no problem creating multiple pools with the same branches with slightly different options.

    omv 5.5.11 usul | 64 bit | 5.4 proxmox kernel | omvextrasorg 5.3.6
    omv-extras.org plugins source code and issue tracker - github


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  • when you create a shared folder do your pools show up with the same name?

    Yep. Probably hard for the OS and/or plugin to differentiate between them. I changed the plugin to allow disks to be used in multiple pools but it was never intended to create identical pools (never tested until now). This isn't something that I will try to fix either (if it is even possible).

    omv 5.5.11 usul | 64 bit | 5.4 proxmox kernel | omvextrasorg 5.3.6
    omv-extras.org plugins source code and issue tracker - github


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  • Yep. Probably hard for the OS and/or plugin to differentiate between them. I changed the plugin to allow disks to be used in multiple pools but it was never intended to create identical pools (never tested until now). This isn't something that I will try to fix either (if it is even possible).

    Huh... So the OS doesn't use the pool name to differentiate? Just the drives in the pool?

  • Huh... So the OS doesn't use the pool name to differentiate? Just the drives in the pool?

    The OS sees different mount points but the branches are identical. Linux can mount the same filesystem multiple times. When I mentioned the OS, I really meant OMV.

    omv 5.5.11 usul | 64 bit | 5.4 proxmox kernel | omvextrasorg 5.3.6
    omv-extras.org plugins source code and issue tracker - github


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  • The OS sees different mount points but the branches are identical. Linux can mount the same filesystem multiple times. When I mentioned the OS, I really meant OMV.

    they have different mount points so they should be able to be identified as unique instances by OMV when adding a new shared folder, right?


    /srv/dev-disk-by-label-5QD5GJQ1:/srv/dev-disk-by-label-5QD47DFQ /srv/643b2a45-44a4-4368-a43d-e9fbc30292f3 fuse.mergerfs defaults,allow_other,direct_io,use_ino,category.create=mfs,minfreespace=4G 0 0
    /srv/dev-disk-by-label-JEH73UM1:/srv/dev-disk-by-label-2YHY6W8D /srv/de2cbcb9-492c-472f-bbe3-d33e735f108f fuse.mergerfs defaults,allow_other,direct_io,use_ino,func.getattr=newest,category.create=mfs,minfreespace=4G 0 0
    /srv/dev-disk-by-label-JEH73UM1:/srv/dev-disk-by-label-2YHY6W8D /srv/4d0cc6bd-6e1d-4e45-a04f-03555cda6b9b fuse.mergerfs defaults,allow_other,direct_io,use_ino,category.create=mfs,minfreespace=12G 0 0

  • they have different mount points so they should be able to be identified as unique instances by OMV when adding a new shared folder, right?

    OMV doesn't differentiate between drives by mountpoint. So, after spending more time looking into this than I wanted to, I don't think the plugin is at fault. OMV uses standard tools (findfs, blkid, etc) that work with true devices but don't work quite right with fuse filesystems especially when there are almost identical setups. All I can say is don't use identical pools.


    One partial solution is to select the drives in a different order when creating the pool since the plugin does know which drives you select first. So:


    pool 1 -> select drive 1 then drive 2 then drive 3
    pool 2 -> select drive 2 then drive 3 then drive 1
    pool 3 -> select drive 3 then drive 1 then drive 2


    I confirmed the above method gets the labels correct when creating a sharedfolder. If you only have two drives in the pool, you can only have two identical pools. This is the best I can offer.

    omv 5.5.11 usul | 64 bit | 5.4 proxmox kernel | omvextrasorg 5.3.6
    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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