Pooling Drives: Aufs, mhddfs, OverlayFS, LVM Confusion

  • As a newbie to OpenMediaVault, I've been reading up as much as I can on how the file system might best be set up for me. At this point it seems like a pooling option combined with Snapraid makes sense. As some background, OpenMediaVault would be primarily media oriented, i.e. large mkv files, etc.). I've also considered running ProxMox on the bare metal base system, and running OpenMediaVault as a container to allow using the server to be utilized for general computer lab purposes. I'd be setting up OpenMediaVault (or ProxMox and VM's) on a SSD, and a pool of hard drives that excludes things that are database driven and change frequently such as Plex housekeeping from Snapraid.


    It appears that each of the pooling options have issues. Aufs apparently has the issue of leaving behind whiteout and opaque files unless fixing and compiling custom kernels, mhdds apparently experiences frequent disconnects (particularly with large files), LVM you loose the array if a drive fails, and OverlayFS seems to be supported sporadically.


    If you were doing a new install without worrying about migrating old data, which option is optimal right now?

    • Offizieller Beitrag

    I use aufs for my media and have never had an issue. Most people don't post that it is working well.


    I haven't heard of disconnects with mhddfs. Speed is the only issue I have heard of.


    You won't lose your lvm if it is on top of raid 5 and one drive fails.


    OverlayFS requires a newer kernel than is available in Wheezy without compiling a newer kernel.

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  • ryecoaaron replied:



    If you google "mhddfs disconnects" you'll see some examples, I don't know how prevalent the issue has been, just that some have had issues. On one site, an article with a how-to for mhddfs and commenting positively was posted after "after being frustrated by the whiteout and opaque files that AUFS was leaving behind", but then in comments on it people were complaining about disconnects. Subsequently the author himself experienced it as well, and posted an article on going back to Aufs with a custom kernel.

    #84 SnapRAID with mhddfs, Jan 03, 2014


    #89 Compile AUFS with 3.18.6 kernel, hnotify, and NFS exportability, Mar 05, 2015


    "I switched back to AUFS from mhddfs because of disconnects whenever I would transfer a decent amount of files to the pool. The only reason I switched to mhddfs originally was because of the annoying whiteout and opaque files. If you compile your own kernel and AUFS version as I show in the comment, and use the notify option, I no longer see those files. AUFS is lighter weight than mhddfs, it's faster, and it handles permissions a little better. Without the .wh/.opaq files, it's really working well."


    Perhaps it is only a problem in specific scenarios. I assume you have not had the Aufs issue with whiteout and opaque files and the need to compile a custom kernel to get NFS exports, it seems like that may be the route for me.


    Thanks for the help.

    • Offizieller Beitrag

    I was only commenting on OMV users. Other distros could be using different versions of aufs/mhddfs/kernel/utilities.


    I don't use nfs with aufs. My aufs setup is my movie collection. I rsync to it from my main server. So, not a lot of writes or deletes. Plenty of reads. This may be why I have had good luck. Removing the wh/opq files seems to fix aufs problems as well.


    If you want maximum compatibility, use mhddfs. On a fast system, the speed penalty isn't that severe.


    Try both :)

    omv 7.0.4-2 sandworm | 64 bit | 6.5 proxmox kernel

    plugins :: omvextrasorg 7.0 | kvm 7.0.10 | compose 7.1.2 | k8s 7.0-6 | cputemp 7.0 | mergerfs 7.0.3


    omv-extras.org plugins source code and issue tracker - github


    Please try ctrl-shift-R and read this before posting a question.

    Please put your OMV system details in your signature.
    Please don't PM for support... Too many PMs!

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