ceph/doc/cephfs/nfs.rst

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===
NFS
===
CephFS namespaces can be exported over NFS protocol using the
`NFS-Ganesha NFS server <https://github.com/nfs-ganesha/nfs-ganesha/wiki>`_.
Requirements
============
- Ceph filesystem (preferably latest stable luminous or higher versions)
- In the NFS server host machine, 'libcephfs2' (preferably latest stable
luminous or higher), 'nfs-ganesha' and 'nfs-ganesha-ceph' packages (latest
ganesha v2.5 stable or higher versions)
- NFS-Ganesha server host connected to the Ceph public network
Configuring NFS-Ganesha to export CephFS
========================================
NFS-Ganesha provides a File System Abstraction Layer (FSAL) to plug in different
storage backends. `FSAL_CEPH <https://github.com/nfs-ganesha/nfs-ganesha/tree/next/src/FSAL/FSAL_CEPH>`_
is the plugin FSAL for CephFS. For each NFS-Ganesha export, FSAL_CEPH uses a
libcephfs client, user-space CephFS client, to mount the CephFS path that
NFS-Ganesha exports.
Setting up NFS-Ganesha with CephFS, involves setting up NFS-Ganesha's
configuration file, and also setting up a Ceph configuration file and cephx
access credentials for the Ceph clients created by NFS-Ganesha to access
CephFS.
NFS-Ganesha configuration
-------------------------
A sample ganesha.conf configured with FSAL_CEPH can be found here,
`<https://github.com/nfs-ganesha/nfs-ganesha/blob/next/src/config_samples/ceph.conf>`_.
It is suitable for a standalone NFS-Ganesha server, or an active/passive
configuration of NFS-Ganesha servers managed by some sort of clustering
software (e.g., Pacemaker). Important details about options are
added as comments in the sample conf. There are options to do the following:
- minimize Ganesha caching wherever possible since the libcephfs clients
(of FSAL_CEPH) also cache aggressively
- fetch Ganesha config files stored in RADOS objects
- store client recovery date in RADOS OMAP key-value interface
- mandate NFSv4.1+ access
- enable read delegations (need at least v13.0.1 'libcephfs2' package
and v2.6.0 stable 'nfs-ganesha' and 'nfs-ganesha-ceph' packages)
Configuration for libcephfs clients
-----------------------------------
Required ceph.conf for libcephfs clients includes:
* a [client] section with ``mon_host`` option set to let the clients connect
to the Ceph cluster's monitors, e.g., ::
[client]
mon host = 192.168.1.7:6789, 192.168.1.8:6789, 192.168.1.9:6789
Mount using NFSv4 clients
=========================
It is preferred to mount the NFS-Ganesha exports using NFSv4.1+ protocols
to get the benefit of sessions.
Conventions for mounting NFS resources are platform-specific. The
following conventions work on Linux and some Unix platforms:
From the command line::
mount -t nfs -o nfsvers=4.1,proto=tcp <ganesha-host-name>:<ganesha-pseudo-path> <mount-point>
Current limitations
===================
- Per running ganesha daemon, FSAL_CEPH can only export one Ceph filesystem
although multiple directories in a Cephfile system may be exported.