Seek advice for using Ceph to provice NAS service

[Jevon Qiao <scaleqiao@gmail.com>]

Hi Sage and other Ceph experts,

This is a greeting from Jevon, I'm from China and working in a company 
which are using Ceph as the backend storage. At present, I'm evaluating 
the following two options of using Ceph cluster to provide NAS service 
and I need your advice from the perspective of stability and feasibility.

Option 1: Directly use CephFS
Since Ceph as a unified storage can provide file system storage service 
via cephfs, this looks an ideal solution for my case if CephFS is ready 
to be used in production environment. However, based on the previous 
discussions on CephFS, I see that there are still some issues like not 
ready for supporting multiple metadata servers, lack of a fully 
functioning fsck and so on. Also, I learn that CephFS has been evaluated 
by a large community of users and there are production systems using it 
with a single MDS from the official website of Ceph. So it is difficult 
for me to make the decision on whether I should use it.

Option 2: Ceph rbd + NFS server
This might be a common architecture used in current NAS storage. But the 
problem is how to get rid of the single point failure on NFS server. 
What I have right now is to use Corosync and Pacemaker(the typical HA 
solution in Linux) to form a cluster. It seems that Sebastien Han has 
verified the feasibility.

Your comments/advices would be highly appreciated and I'm looking 
forward to your reply.

Thanks,
Jevon