After installing rocks and the compute nodes you must export the user data drives from the frontend to the nodes. This is guide is from http://www.rocksclusters.org/assets/usersguides/roll-documentation/base/6.2/faq-configuration.html#EXPORT.
1) Add the directory to export to the /etc/exports
file, e.g.:
/export 10.1.1.1(rw,async,no_root_squash) 10.1.0.0/255.255.0.0(rw,async)
/export2 10.1.1.1(rw,async,no_root_squash) 10.1.0.0/255.255.0.0(rw,async)
/export3 10.1.1.1(rw,async,no_root_squash) 10.1.0.0/255.255.0.0(rw,async)
/export4 10.1.1.1(rw,async,no_root_squash) 10.1.0.0/255.255.0.0(rw,async)
2) Restart NFS: /etc/rc.d/init.d/nfs restart