GlusterFS

Installation
yum install centos-release-gluster39 -y
yum install glusterfs-server -y

service glusterd start

# from server1
gluster peer probe server2

# from server2
gluster peer probe server1

# on both make a new disk (vdb1) for bricks
echo "/dev/vdb1 /mnt/vdb1 ext4 defaults 0 0" >> /etc/fstab
mount /dev/vdb1 /mnt/vdb1
# make a new folder for brick (gluster0)
mkdir /mnt/vdb1/gluster0

# create mirror from any
gluster volume create gv0 replica 2 app1:/mnt/vdb1/gluster0 app2:/data/vdb1/gluster0
gluster volume start gv0

# mount cluster vol on both
echo "app1:/gv0 /data    glusterfs defaults,_netdev 0 0" >> /etc/fstab
mount -t glusterfs server1:/gv0 /data

# status
gluster volume list
gluster volume info
gluster volume status
gluster peer status

# performance tuning on both
# http://gluster.readthedocs.io/en/latest/Administrator%20Guide/Managing%20Volumes/
gluster volume set gv0 performance.cache-size 1GB
gluster volume set gv0 performance.client-io-threads on
gluster volume set gv0 performance.io-thread-count 16
gluster volume set gv0 performance.readdir-ahead enable
gluster volume set gv0 cluster.readdir-optimize on
gluster volume set gv0 client.event-threads 3
gluster volume set gv0 server.event-threads 3

# healing 
volume heal 

# removing
gluster volume stop gv [force]
gluster volume delete gv