====== GlusterFS ======
I use glusterfs to mirror a directory between cluster members.
cd /usr/src
wget -c ftp://gluster.org/pub/gluster/glusterfs/3.0/LATEST/glusterfs-3.*.tar.gz
aptitude install build-essential flex bison fuse-utils
tar xvzf glusterfs-3.*.tar.gz
cd glusterfs-3.*
./configure --sysconfdir=/etc --localstatedir=/var && make -j2 && make install
cd /etc/glusters
glusterfs-volgen -n data -r 1 -a 10.1.1.* server1:/data server2:/data
ln -s server1-data-export.vol glusterfsd.vol
ln -s data-tcp.vol glusterfs.vol
update-rc.d glusterfsd defaults
glusterfs.vol:
...
volume mirror-0
type cluster/replicate
subvolumes server1-1 server2-1
option read-subvolume `hostname`-1
end-volume
...
/etc/fstab:
/etc/glusterfs/glusterfs.vol /nas glusterfs defaults 0 0