Migrate zfs pool drives.md

Migrate ZFS pool drives

If you want to migrate your pool to other disks, maybe to larger ones, you can follow the following steps. If you have 3 to 4 disks, raidz is recommended. If you have 5 to 6 disks, raidz2 is recommended. Less than 3 disks is not recommended since the only possible redundancy would be with 2 disks in mirror mode with only one redundancy disk and only 50% capacity. For more than 6 discs it is recommended that you make 2 or more pools.

Steps

1. After logging in, assume root by running sudo -i.
2. Run: ./scripts/migrate_pool.sh Tank raidz2 /dev/disk/by-id/disk1 /dev/disk/by-id/disk2 /dev/disk/by-id/disk3 /dev/disk/by -id/disk4 /dev/disk/by-id/disk5 /dev/disk/by-id/disk6. It is assumed that the new pool will use the same key as the previous one and that it is already in place. Tank is the name of the current pool. It is the same name used by the script that initially creates the pool. The other parameters are the same as for create_zfs_pool.sh. See information in section Create ZFS pool.
3. Mount all datasets and load the key if necessary: zfs mount -al.
4. Run: ./scripts/generate_dataset_mount_units.sh. This will generate Systemd units that will mount the datasets in Tank automatically after loading the key upon rebooting the server. Run this command cat /etc/zfs/zfs-list.cache/Tank to verify that the cache file is not empty. If it is empty, try running the script again as it means the cache and units were not generated.

Note

After migration, there will be certain steps in the guide that you can skip. For example if certain directories or files already existed. It is left to the reader's discretion to see which steps are no longer necessary.

Tip

To adjust the max size of ZFS ARC use the command echo {size_in_bytes} > /sys/module/zfs/parameters/zfs_arc_max replacing {size_in_bytes} with the size in bytes you wish to set. To make the change permanent execute the command echo "options zfs zfs_arc_max={size_in_bytes}" > /etc/modprobe.d/zfs.conf && dracut --force.

Caution

Assigning a very high value can cause instability in the system, only change it if you know what you are doing.