TLDR: I am running some Docker containers on a homelab server, and the containers’ volumes are mapped to NFS shares on my NAS. Is that bad performance?

  • I have a Linux PC that acts as my homelab server, and a Synology NAS.
  • The server is fast but has 100GB SSD.
  • The NAS is slow(er) but has oodles of storage.
  • Both devices are wired to their own little gigabit switch, using priority ports.

Of course it’s slower to run off HDD drives compared to SSD, but I do not have a large SSD. The question is: (why) would it be “bad practice” to separate CPU and storage this way? Isn’t that pretty much what a data center also does?

  • @Molecular0079English
    22•1 year ago

    I wouldn’t recommend running container volumes over network shares mainly because network instability between NAS and server can cause some really weird issues. Imagine an application having its files ripped from underneath them while they’re running.

    I would suggest containers + volumes together on the server, and stuff that’s just pure data on the NAS. So for example, if you were to run a Jellyfin media server, the docker container and its volumes will be on the server, but the video and audio files will be stored on the NAS and accessed via a network share mount.

    • @PlutoniumAcidOPEnglish
      5•1 year ago

      I think you are saying what I am also saying, but my post was not clear on this:

      The container files live on the server, and I use the volume section in my docker-compose.yml files to map data to the NFS share:

              volumes:
            - '/mnt/nasvolume/docker/picoshare/data:/data'

      Would you say this is an okay approach?

      • @Molecular0079English
        9•1 year ago

        Mmm, not quite. I am not familiar with how picoshare works exactly, but according to the picoshare docker README, it uses the data volume to store its application sqlite database. My original suggestion is that the Docker application and its application data (configs, cache, local databases, and other files critical to the functioning of the application) should be on the same machine, but the images and other files that picoshare shares can be remote.

        Basically, my rule is to never assume that anything hosted on another machine will be guaranteed to be available. If you think picoshare can still work properly when its sqlite database gets ripped out without warning, then by all means go for it. However, I don’t think this is the case here. You’ll risk the sqlite database getting corrupted or the application itself erroring out if there’s ever a network outage.

        For example, with the Jellyfin docker image, I would say that the cache and config volumes have to be local, while media can be on a remote NAS. My reasoning is that Jellyfin is built to handle media files changing / adding / disappearing. It is however, not built to gracefully handle its config files and caches disappearing in the middle of operation.

    • Norah - She/TheyEnglish
      3•1 year ago

      There are also situations where you can do it safely if there’s already the ability for remote communication built in. I have some MariaDB containers on a different machine to what’s using and serving the data. I could’ve had them in the same Compose file on the one machine, communicating over an internal Docker network. Instead I just changed it to point at an external port instead.

      • @Molecular0079English
        4•1 year ago

        Agreed! If the application can handle these files (or other resources) disappearing for a while during network issues, then sure, they can be separate. However, if an application depends on a file for its core functionality, I do not think it is a good idea.