If you are using CEPH, CephFS is an option for you. If you can set up additional devices or have them anyway (like a NAS) you can do it over that. If you don't have or can't do one or the other, GlusterFS would be a solution for you.
Otherwise, you could set up a VM on the cluster that does NFS, but I would personally advise against creating a chicken-and-egg problem here.