====== MergerFS - Add a new data disk ======

===== View the current setup =====

Install the xattr utility tool:

<code bash>
apt install python-xattr
</code>


Assuming the root of the mergerfs filesystem is /storage, use xattrs to view the pseudo .mergerfs file:

<code bash>
cd /storage
xattr -l .mergerfs
</code>

returns:

<code>
user.mergerfs.srcmounts: /mnt/data/disk01:/mnt/data/disk02:/mnt/data/disk03
user.mergerfs.minfreespace: 21474836480
user.mergerfs.moveonenospc: true
user.mergerfs.policies: all,eplfs,eplus,epmfs,erofs,ff,lfs,lus,mfs,newest,rand
user.mergerfs.version: 2.13.1
user.mergerfs.pid: 91089
user.mergerfs.category.action: all
user.mergerfs.category.create: eplfs
user.mergerfs.category.search: ff
user.mergerfs.func.access: ff
user.mergerfs.func.chmod: all
user.mergerfs.func.chown: all
user.mergerfs.func.create: eplfs
user.mergerfs.func.getattr: ff
user.mergerfs.func.getxattr: ff
user.mergerfs.func.link: all
user.mergerfs.func.listxattr: ff
user.mergerfs.func.mkdir: eplfs
user.mergerfs.func.mknod: eplfs
user.mergerfs.func.open: ff
user.mergerfs.func.readlink: ff
user.mergerfs.func.removexattr: all
user.mergerfs.func.rename: all
user.mergerfs.func.rmdir: all
user.mergerfs.func.setxattr: all
user.mergerfs.func.symlink: eplfs
user.mergerfs.func.truncate: all
user.mergerfs.func.unlink: all
user.mergerfs.func.utimens: all
</code>

<WRAP info>
**NOTE:**  This shows that there are 3 disks in the pool, namely:

  * /mnt/data/disk01
  * /mnt/data/disk02
  * /mnt/data/disk03


All of options shown can be set in real time without unmounting and re-mounting the mergerfs pool via the runtime options.

</WRAP>

----

===== Add a disk =====

From within the root of the mergerfs filesystem (eg. /storage)

<code bash>
xattr -w user.mergerfs.srcmounts '+>/mnt/data/disk04' .mergerfs

or, for adding two disks use:

xattr -w user.mergerfs.srcmounts '+>/mnt/data/disk04:/mnt/data/disk05' .mergerfs
</code>

<WRAP info>
**NOTE:**  This will append disk04 and disk05 onto the end of the current srcmounts.
</WRAP>