Removing a Disk from Mergerfs Pool & Replacing

1st Official Post

    I have looked into doing the above but this is the first time trying to do this. I'm not very good with words and a guide with pictures of each step or a video tutorial to follow would help me so much.


    I have a 4 Bay server that is running OMV 6 and all bays are populated. I want to remove the smallest disk, a 4Tb Drive but first add the data on that drive onto the Mergerfs Pool. Then look to remove the Disk and replace that with a 14Tb drive. Also how would I add this new drive to the mergerfs pool correctly?


    I looked at this site in the docs and wondered if theres a step by step guide of how to run this process. I'm not very good with the written word but with pictures and videos I can follow a tutorial. I found this below but not sure if this is correct way to do it


    Many thanks in advance


    omv6:omv6_plugins:snapraid [omv-extras.org]

    • Official Post

    As far as I know, there's no video tutorial for doing a drive replacement, in a MergerFS pool. So...
    ________________________________________________

    (After moving all data from the disk to be removed, to other drives in the MergerFS pool.)

    ** Don't forget to format and mount the new 14TB drive, before adding it to the MergerFS pool. **
    _________________________________________________

    Replacing the drive, in the pool, is done as the SnapRAID document illustrates, starting -> here.

    It's pretty straight forward:
    The process is finding the exact path to the drive that's been removed, and replacing that entry with the exact path to the new drive, in the list of drive entries that make up the MergerFS pool. The procedure walks through how to do it.

    Once the 14TB drive is installed and part of the pool, the balance tool could be used to re-balance storage.

    Quote from crashtest

    As far as I know, there's no video tutorial for doing a drive replacement, in a MergerFS pool. So...
    ________________________________________________

    (After moving all data from the disk to be removed, to other drives in the MergerFS pool.)

    Thanks for the reply


    Regarding the above what is the EXACT process to move that data from the 4Tb disk to the rest of the mergerfs pool?


    I can take screenshots of my disks on the OMV GUI to get the right help? If you could inform me what part of the GUI I need to go to and the process that would help me a lot.


    I know it may be a very easy process but I really dont wanna screw it up

    Install a copy of Midnight Commander and learn how to use it.

    --
    Google is your friend and Bob's your uncle!


    OMV AMD64 7.x on headless Chenbro NR12000 1U 1x 8m Quad Core E3-1220 3.1GHz 32GB ECC RAM.

    Quote from gderf

    Install a copy of Midnight Commander and learn how to use it.

    I have MC and have used it before when I setup my Plex, Radarr & Sonarr with TrashGuides.


    1. How would I use it to move data from the 4Tb to the other disks on in the pool?

    2. I think I understand your process - once thats done I sud be able to remove the 4Tb from the mergerfs pool and remove the drive from the server.

    3. Then I can put in the 14tB new disk to the server - mount it to OMV and format it before adding it to the pool and then running the balance tool.


    Please tell me if this is correct?

    • Official Post
    Quote from DNUKaen

    How would I use it to move data from the 4Tb to the other disks on in the pool?

    Which part is not clear?


    How to Use Midnight Commander, a Visual File Manager
    This guide shows how to install and use Midnight Commander, a text user-interface file manager.
    www.linode.com

    Can anyone inform me where I should aim the data to be transferred from the right disk? Do I need to put in a certain folder? When I have checked what is on that disk in MC there are 5 folders - would I transfer the data from those folders to the same corresponding folders on another disk?


    Then remove that disk from the mergerfs pool and remove the disk from the server and replacing it with the new one and run through the SnapRAID process mentioned in comment No. 2

    • Official Post

    (Assuming that you have a free USB connection)

    Have you thought about getting a drive dock? With a single drive dock, you could copy the entire contents of the drive to be replaced, to the new 14TB drive, with an rsync command line. (It would take awhile for the copy to complete.)

    At that point, it would be a matter of swapping the 14TB drive into the enclosure and changing the drive entry in MergerFS.

    That might simplify things for you.

    Quote from crashtest

    Have you thought about getting a drive dock? With a single drive dock, you could copy the entire contents of the drive to be replaced, to the new 14TB drive, with an rsync command line. (It would take awhile for the copy to complete.)

    There is a USB on the Server Box but again what would be the process to do this to transfer the data?


    I'm happy to use the MC way but its how to do it if the process is explained. I have the program and have used it before but just wondering where the data from the disk, which I have found, needs to be moved. I can then unmount and then workout how to add the new drive.


    As Ive mentioned Im happy to follow a process if someone spells out that process for me

    • Official Post

    "With a drive dock and the new 14TB (formatted and mounted) drive"

    The process would be:

    1. Use an rsync command line to copy the 4TB drive you're replacing, to the new 14TB drive. In the overview, the command line would be something like this. (This is an example only.)

    Existing Source Drive Destination 14TB drive
    rsync -av /srv/dev-disk-by-uuid-3bdb3de5-218b-4930-bb61-05cda64f8c6b/ /srv/dev-disk-by-uuid-dfa2df17-9764-4a47-8e9d-9a36ff74ca37/


    - Figuring out how to construct the rsync command line is covered here -> Full Disk Mirroring / Backup with Rsync. The guidance will show you how to find drives, in the filesystems window, and how to copy and paste the UUID's of each drive. Notice, in the example above, that the --delete switch is NOT used. Don't add it to your line.

    - If you don't want to get on the command line, you can use a Scheduled Task in the GUI, as shown in the Full Disk Mirroring guidance, to run the command. If you use a Scheduled Task, do not "Enable" it to run automatically. Run the task manually.

    - When the task is running from the GUI, a window will come up that starts with sending incremental files list. When that's done, it will proceed to a scrolling files list as files are copied.

    I don't know how much data you'll be coping. Over USB (2.0?), it may take several hours to even days. If you close the Browser GUI window, you'll have no indication that the task is still running. The best way to insure that the task is still running is to run it again. If the task is still running, in the background, you'll get "Error" failed to execute, etc., etc.

    If you really want to reestablish the scrolling files window, reboot the server from the GUI. This is fine. Running the Scheduled Task, after the reboot, will pick up exactly where it left off. Depending on power flops and other events, you may have to run the rsync command line a few times to get the copy to completion.

    You'll know when the rsync copy task is fully complete when you get something like the following:

    sent 260,237,726 bytes received 26,993 bytes 3,744,816.10 bytes/sectotal size is 53,268,665,531 speedup is 204.67The synchronisation has completed successfully.

    END OF LINE


    2. At that point, you'd physically swap in the 14TB drive.

    3. Then you would change the member Drive lines in MergerFS according to the guidance found at the end of the SnapRAID document, -> Replacing a Failed Drive in MergerFS. to remove the old drive and add the 14TB drive.


    4. Finally, unmount and remove the entry for the old now "missing" 4TB drive, from the File Systems window, in the GUI.

    Thank you so much for doing the above - this is what I needed. Again thank you so much for this.


    I have just a couple of questions:


    1. I have a HP Proliant Gen 8 Microserver - it has USB on it - Will OMV pick this up?


    2. "With a drive dock and the new 14TB (formatted and mounted) drive" - by this do you mean just a normal format of the drive or do I have to format it with OMV? If so, how would I do this with the 14Tb connected to the servers USB?


    3. Use an rsync command line to copy the 4TB drive you're replacing, to the new 14TB drive. In the overview, the command line would be something like this. (This is an example only.)


    Existing Source Drive Destination 14TB drive

    rsync -av /srv/dev-disk-by-uuid-3bdb3de5-218b-4930-bb61-05cda64f8c6b/ /srv/dev-disk-by-uuid-dfa2df17-9764-4a47-8e9d-9a36ff74ca37/


    Im happy to use command line - But to confirm - this would need me to ssh into the server (then not use a User but just into the server) and run the rsync command. Once completed follow steps 2-4

    • Official Post
    Quote from DNUKaen

    1. I have a HP Proliant Gen 8 Microserver - it has USB on it - Will OMV pick this up?

    Yes. Most USB drive docks, with a drive in them, will show up in OMV. (If the drive doesn't show up, return the dock.)


    Quote from DNUKaen

    2. "With a drive dock and the new 14TB (formatted and mounted) drive" - by this do you mean just a normal format of the drive or do I have to format it with OMV? If so, how would I do this with the 14Tb connected to the servers USB?

    The drive, in the USB dock, will format the same way that it would if it was installed in the server. (But note that formatting a 14TB drive, to EXT4, will take longer than it did when formatting a 4TB drive.)


    Quote from DNUKaen

    Im happy to use command line - But to confirm - this would need me to ssh into the server (then not use a User but just into the server) and run the rsync command. Once completed follow steps 2-4

    You don't have to use SSH, to use the rsync command line, unless you want to.

    The Drive-to-Drive mirroring instructions assumes that you'll save the command line into a Schedule Task, in the GUI. (And it provides the steps to do it.) This works fine. Running a Scheduled task, manually in the GUI, is arguably better. Once the command line is created and saved into a Scheduled Task, you can run it as many times as needed without the need to recreate it. (When you're done and all is working, you can delete the scheduled task or keep it as an example.)

    Just remember, the source drive (4TB) is on the left and the destination (14TB) is on the right.

    Quote from crashtest

    The drive, in the USB dock, will format the same way that it would if it was installed in the server. (But note that formatting a 14TB drive, to EXT4, will take longer than it did when formatting a 4TB drive.)

    Regarding this point - I have to find the drive in OMV GUI and format it or do I just format it in EXT4

    • Official Post
    Quote from DNUKaen

    Regarding this point - I have to find the drive in OMV GUI and format it or do I just format it in EXT4

    Yes. Its' the same process you did when you installed any of the 4 drives in your server. There's no difference. It's covered -> here.

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