Balance files across multiple disks using MergerFS
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MergerFS is a great filesystem for an expandable storage system in a homelab. Mostly since it allows you to add disks one at a time without having to, for example, resilver a ZFS pool. MergerFS won’t be as efficient as a filesystem that stripes your data across disks, but in the case of a disk failure the disks unaffected will still have the files assigned to them.
Plenty of other people described MergerFS, so I’ll keep this post simple.
First install MergerFS,
sudo apt install mergerfs
The way I have my drives in my homelab setup is to have /mnt/data/N where N is the number of the drive.
Examples: /mnt/data/1, /mnt/data/2, /mnt/data/3
This is mainly so that I can use wildcards to capture all the drives at once.
Temporary mounting solution:
sudo mergerfs -o defaults,allow_other,use_ino,fsname=data /mnt/data/\* $HOME/data
Permanent solution (Edit /etc/fstab)
/mnt/data/* /home/user/data fuse.mergerfs defaults,allow_other,use_ino,fsname=data 0 0
Quick summary of options passed
| Option | Description |
|---|---|
| defaults | Shortcut for atomic_o_trunc, auto_cache, big_writes, default_permissions, splice_move, splice_read, splice_write |
| allow_other | Allows users beside the mergerfs owner to view the filesystem. |
| use_ino | MergerFS supplies inodes instead of libfuse |
| fsname | Name of the mount as shown in df and other tools |