With this setup we will make two servers using a shared storage as high availabile mount. Both of them host the data, if
one of them is down, the other one will stay the source of truth for so long. Disadvantage of this approach is, that the
files exist 4 times: at server1 and server2 each with
/mnt/barrel (the mounted directory) +
(the glusterfs working directory).
Install glusterfs server and client
On both machines run as root:
$ sudo apt-get install glusterfs-server glusterfs-client
This makes the glusterfs server available and will allows us to connect to the server later on.