ZFS BTRFS recommendation

  • Hello,


    i like to setup another new OMV system.
    My questions for a solid "filesystem":


    1: is it currently ok for protect data (checksum/bitrot) to choose ZFS. Can i absolutely trust ZFS on OMV? (Data protection and handling on gui) (I would choose 3way mirroring with backups...)


    2: Are there deficits in ZFS on OMV? Exepct known kernel dependencies.


    3: is it better to wait for OMV5 USUL with BTRFS support?


    4: How is ZFS implemented in OMV (FUSE?)?


    5: Actually openmediavault-omvextrasorg v.5 was released. Is OMV5 to be expect in the near future?


    thank you much for your answers

  • Can i absolutely trust ZFS on OMV?

    You need to ask if you can trust ZFS on Debian and I would say yes.


    Are there deficits in ZFS on OMV? Exepct known kernel dependencies.

    There might be a couple of features that aren't available in the plugin but you can do that from the command line. If you are worried about the kernel, use the proxmox kernel (installable from omv-extras) which will use the proxmox zfs packages that are well tested together.


    is it better to wait for OMV5 USUL with BTRFS support?

    As far as I know, OMV 5 is nowhere near release. If you desire if for stability, OMV 4 is a better option.


    How is ZFS implemented in OMV (FUSE?)?

    Kernel module compiled (zfs-dkms) for the system's kernel. Definitely not fuse.


    Actually openmediavault-omvextrasorg v.5 was released. Is OMV5 to be expect in the near future?

    The release date for OMV 5 has nothing to do with omv-extras packages in the repo. That is just me doing initial ports to OMV 5 so that I don't fall behind. As far as I know, it isn't near.

    omv 6.0.8-1 Shaitan | 64 bit | 5.15 proxmox kernel | omvextrasorg 6.0.5 | kvm plugin 6.0.3
    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!

  • OMV4 (Debian 9) supports btrfs for data drives already


    Two small notes:

    • Since almost all the relevant code lives inside the kernel choosing the most recent kernel version possible is IMO a must with btrfs (on x64 at least using backports kernel and with ARM devices avoiding everything that is not at least on kernel 4.4)
    • Unfortunately the attractive btrfs features (snapshots, the non-anachronistic btrfs mirror mode and so on) are not really supported. But 3rd party tools like btrbk work quite well with OMV)
  • @macom, @tkaiser : do you have OMV 4 running over BTRFS? Could you describe your setup (notably which kernel do you use, what fs you use for system drive) and also, if you were on ext4, how did you migrate?
    Thank you!

  • For me ZFS and BTRFS are not ready. They lack the fundamental tools to allow a normal user to take full advantage of the features. As it is you need to make a significant effort to learn how to use the features. I still haven't bothered. I suspect Ubuntu 20.04 will include some tools for managing ZFS and make use of the features. Let's hope these tools allow remote use over ssh.


    Live snapshots. Automatic bitrot detection and correction using redundant and/or remote copies of the filesystem.

    Be smart - be lazy. Clone your rootfs.
    OMV 5: 9 x Odroid HC2 + 1 x Odroid HC1 + 1 x Raspberry Pi 4

  • do you have OMV 4 running over BTRFS? Could you describe your setup (notably which kernel do you use, what fs you use for system drive) and also, if you were on ext4, how did you migrate?

    On the HC2 I use btrfs on the OS filesystem as well as on the HDD.
    On the other NAS I use btrfs on one drive and ext4 on the other.


    On both I use the standard kernel which comes with OMV. Updated when a new one is available.
    I did not migrate an existing fs, but created fresh ones.

  • I installed the module, it compiled the ZFS modules, and I created a ZFS pool with no issues, been running solid as a rock!


    Anything other than doing basic monitoring or seeing how the pool is doing, and adding sub folders, and filesharing, I do everything else command line, which is VERY easy


    More or less if it works on debian...it works just fine on OMV
    https://unix.stackexchange.com/questions/383566/install-zfs-on-debian-9-stretch


    plus there are tons of cheatsheet links out there for ZFS


    The DOCS point to this repository that has more info...but by adding OMV-Extras then the ZFS module it does it all pretty much automatically
    https://github.com/zfsonlinux/zfs/wiki/Debian

  • Does ZFS use a lot of RAM?

    NAS: OMV6
    (Intel i5 4570❄Gigabyte GA-H97N-WIFI❄12GB DDR3❄SSD EVO850➕WD Red Plus 4TB x 2➕WD Gold 8TB➕Exos 10TB)
    Gigabit Internet➕Mikrotik hAP ac²

  • All the RAM you have. All filesystems do that. But ZFS can also use RAM for a more persistent cache with slightly better performance. This makes ZFS faster in some cases. But at the cost of a lot of RAM. You can get similar or even much greater speedups using for instance bcache, using a SSD in front of spinning rust. Client side caching of NFS is also an option that can yield tremendous speedups, much, much greater than what ZFS on a NAS can achieve.


    Before you decide to use something other than EXT4 you should test it very carefully. And make sure that YOU are able to use it.


    Both BTRFS and ZFS are superior to EXT4. But only if you know how to take advantage of the superior features. In professional settings for example, where the knowledge can be applied to many systems and used to speed up backups and restores and improve data integrity. If you don't already have the knowledge and skill required, you may be worse of using BTRFS or ZFS instead of EXT4, unless you make an effort to learn.


    Use a dummy test system to learn.

    Be smart - be lazy. Clone your rootfs.
    OMV 5: 9 x Odroid HC2 + 1 x Odroid HC1 + 1 x Raspberry Pi 4

  • If you do not use deduplication , RAM is not a problem , with 2GB min, you can play.

  • Both BTRFS and ZFS are superior to EXT4.

    I have switched back to ext4 after 1 day using of btrfs. Don`t know why but btrfs was much slower then ext4 with the same data (after formatting I copied back my 1TB of data) and I wasn`t able to run 'balance' command, also I have noticed that when I tried to open some folders which located on btrfs - I had little delay each time.


    I think about ZFS, but I have only 8GB of RAM now and non-ECC, so I `m not sure should I add extra 8GB of RAM (the same non-ECC, because I have intel-i5), would it be fine or current 8GB is already enough?


    Currently I want to use only 3TB HDD in ZFS, but if it`s really good file system I will use it on another 6 and 8 TB HDD`s, so no raid only 3 different HDD = 17 TB.

    NAS: OMV6
    (Intel i5 4570❄Gigabyte GA-H97N-WIFI❄12GB DDR3❄SSD EVO850➕WD Red Plus 4TB x 2➕WD Gold 8TB➕Exos 10TB)
    Gigabit Internet➕Mikrotik hAP ac²

  • And sorry, last question:

    What is the flow of switching to ZFS:

    1. Install Proxmox kernel

    2. Remove non-Proxmox kernels and headers

    3. Install ZFS plugin

    Am I correct? Or something else is required.

    NAS: OMV6
    (Intel i5 4570❄Gigabyte GA-H97N-WIFI❄12GB DDR3❄SSD EVO850➕WD Red Plus 4TB x 2➕WD Gold 8TB➕Exos 10TB)
    Gigabit Internet➕Mikrotik hAP ac²

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