Questions about Raid1 Capacity

    • OMV 4.x
    • Questions about Raid1 Capacity

      Hi All,

      I recently re-purposed my old gaming PC into a NAS with Openmediavault using Techno Dad Life's video (youtube.com/watch?v=NYJCq2FwRUo).

      I have a question about my Raid1 (mirror) capacity.

      My drives were setup per the video of which there are three drives (1x 1.83tb and 2x 2.73tb):



      Under raid management it looks like there are two items (from the 3x drives):




      However under File systems there is only Raid drive with 1.83tb (I thought it should be higher as there is around 7tbs worth of storage):


      Hopefully this makes sense as it's hard to explain. I was thnking there should be closer to 3.5tb storage rather than 1.79tb....

      Cheers
    • Your setup makes not that much sense. You mirrored two 3TB drives and then create another mirror with another 2TB drive and the first mirror therefore limiting the usable capacity to the smallest member: 2TB.

      Stalukes wrote:

      I was thnking there should be closer to 3.5tb storage
      For this you need to adopt more reasonable attempts than (close to) useless RAID1: With a btrfs raid1 made out of these three drives you end up with a usable capacity slightly above 3.5TB (explanation). With btrfs you also get a few other benefits (but unfortunately btrfs support in OMV4 isn't that advanced so only do this if you really know what you're doing):
      • bitrot protection!
      • flexible dataset/subvolume handling overcoming partition limitations
      • transparent filesystem compression
      • snapshots (freezing a filesystem in a consistent state)
      • ability to efficiently send snapshots to another disk/host (backup functionality)
      • immune to power failures due to CoW (Copy on Write)
      No more contributions to this project until 'alternative facts' (AKA ignorance/stupidity) are gone

      The post was edited 1 time, last by tkaiser ().

    • Stalukes wrote:

      I thought it should be higher as there is around 7tbs worth of storage
      Maybe you should have a look at the unionfilesystem-plugin which uses mergerfs. It allows to combine several drives to one mount point. So the total capacity is the sum of the capacity of the individual drives. But it does not have the benefits tkaiser was mentioning.
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    • Hi guys,

      Thank you very much for your replies. I have definitely made a mistake as you've mentioned and am very green to all this!

      I really just want to use the drives efficiently to backup my media and play it on Plex, if there's a raid configuration that adds extra security/redundancy I'm all ears.

      It sounds like a btrfs raid1 would be the way to go but I'm no expert. Can you recommend any tutorial videos I could watch to setup my drives in a more efficient way?

      Thanks
    • Stalukes wrote:

      It sounds like a btrfs raid1 would be the way to go but I'm no expert. Can you recommend any tutorial videos
      Nope (not a fan of video tutorials anyway).

      While such a 'btrfs raid1' will do what you want (using some redundancy to protect the data and ending up with half the capacity usable for your data) as already said btrfs integration in current OMV versions is still lacking.
      No more contributions to this project until 'alternative facts' (AKA ignorance/stupidity) are gone