Migration to UnionFS + SnapRaid: recommendations

    • OMV 4.x
    • Resolved
    • Migration to UnionFS + SnapRaid: recommendations

      Hello forum!

      My current OMV server currently has only one 1 TB HDD for my data (Data1), which I regularly back up to an external USB HDD. OMV runs on a separate SDD. Since the HDD is getting slowly full, I wanted to move to a HDD pool + SnapRaid to make it easy to expand the storage in the future. However, I have a few doubts regarding the best way to create the pool, and how to migrate my current system to minimize the work required.

      Creating the pool

      My current HDD is at roughly 70% of its capacity. I wanted to simply add a new HDD, create a pool and that's it. However, since the old HDD is mostly full, even if I set UnionFS policy to "most free space", the majority of the data will be still in the old HDD. My rationale here is that I would like to have the data evenly distributed between the drives to gain a little in read/write performance. I have 2-3 users using the server, and having the data spread across the drives should should improve the performance of the HDD pool. Therefore, from the following options what would be the best?

      1. Keep the old drive as it is, add a new drive to the pool and set UnionFS policy to "most free space".
      2. Backup the data from the old drive, erase it, create a pool with the old and new drives, and copy the data again to the pool. UnionFS policy: most free space.
      3. Keep the old drive as it is, add a new drive, move some data to the new drive; and finally create a pool (UnionFs policy: most free space).

      Renaming the HDD pool

      Another concern that I have is renaming the pool. I have several services running, all of them using the name of my current HDD drive. When I create the pool in UnionFS, how does it work with the name of the pool? For example, my music folder is under /srv/VeryLongHDDName/Music. My Plex library is linked to that folder. When I create the HDD pool, how can I update the location of my music folder without having to rebuild my Plex library? Is it possible to simply update the location of the music library and Plex Database?

      Thanks for the advice!
      Custom mini-ITX build
      Coolcube Mini, Intel Desktop Board DQ77KB, Intel Core i3-3220, 8 GB DDR3 Ram, 30 GB Sandisk SSDnow 200 (OS), 1 TB Samsung M8 HN-M101MBB

      Dell Optiplex 960 sff (deprecated) - link


      Dell Optiplex FX160 (repurposed) - link

      "If you can't find it in Google, it simply doesn't exist!" - The Internetz

    • New

      Replying to myself, I completed the migration. My plan was for the drives in the pool to fill up evenly. This was not possible with the configuration I had before. If I simply kept the first drive (Data1) with the my data on it, and add it with a new drive (Data2) to a pool, it was not possible to get UnionFS to put newly created files in Data2, despite having selected the "most free space" policy. In the end, I move all my files out to a back up drive, wiped both Data1 and Data2 and created the pool. I then created my shares directly in the new pool drive, set the policy to "most free space" and copied my data back. Both hard drives filled up evenly this time, with the files spread across both of them.

      The pool drive has of course a different name. I could not find a simple way to rename the it to match the name of my old drive. Therefore, I ended up updating all my SMB shares to point to the newly created pool drive. Plex was kind of a headache, and I ended up recreating my Plex library from the ground. It took some time, but it was worth.

      Finally, for Snapraid I used the following guide: forum.openmediavault.org/index…reconnect-shared-folders/
      Custom mini-ITX build
      Coolcube Mini, Intel Desktop Board DQ77KB, Intel Core i3-3220, 8 GB DDR3 Ram, 30 GB Sandisk SSDnow 200 (OS), 1 TB Samsung M8 HN-M101MBB

      Dell Optiplex 960 sff (deprecated) - link


      Dell Optiplex FX160 (repurposed) - link

      "If you can't find it in Google, it simply doesn't exist!" - The Internetz

    • New

      Thanks for posting this. I'm about to undergo the same migration. I'm currently using mdadm raid1 and I have around 3-4 extra hard drives sitting around without use. A new motherboard is on the way with 6 SATA connections so I should have the ability to add a bunch of space into a pool. I figured I'd have to blank things out so had already planned it...sounds like you found the same. Anyway, appreciate the info!
    • New

      devnet wrote:

      Thanks for posting this. I'm about to undergo the same migration. I'm currently using mdadm raid1 and I have around 3-4 extra hard drives sitting around without use. A new motherboard is on the way with 6 SATA connections so I should have the ability to add a bunch of space into a pool. I figured I'd have to blank things out so had already planned it...sounds like you found the same. Anyway, appreciate the info!
      I followed the advice suggested by other posts on the forum, and the general advice was to create the shares directly in the pooled drive, which meant starting from scratch.

      Be aware that one parity drive is enough for up to 4 data drives. If you plan using 6 drives, you'll need two parity HDDs.

      Greetings!
      Custom mini-ITX build
      Coolcube Mini, Intel Desktop Board DQ77KB, Intel Core i3-3220, 8 GB DDR3 Ram, 30 GB Sandisk SSDnow 200 (OS), 1 TB Samsung M8 HN-M101MBB

      Dell Optiplex 960 sff (deprecated) - link


      Dell Optiplex FX160 (repurposed) - link

      "If you can't find it in Google, it simply doesn't exist!" - The Internetz

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