doc : pNFS support for gluster volumes

Change-Id: I910f8f786849b4ece3d3c258c2c52537edc173dd
BUG: 1209380
Signed-off-by: Jiffin Tony Thottan <jthottan@redhat.com>
Reviewed-on: http://review.gluster.org/10145
Reviewed-by: Kaleb KEITHLEY <kkeithle@redhat.com>
Reviewed-by: soumya k <skoduri@redhat.com>
Reviewed-by: Humble Devassy Chirammal <humble.devassy@gmail.com>
Tested-by: Humble Devassy Chirammal <humble.devassy@gmail.com>

1 files changed, 56 insertions, 0 deletions

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+# How to export gluster volumes using pNFS?
+
+The Parallel Network File System (pNFS) is part of the NFS v4.1 protocol that
+allows compute clients to access storage devices directly and in parallel.
+The pNFS cluster consists of MDS(Meta-Data-Server) and DS (Data-Server).
+The client sends all the read/write requests directly to DS and all other
+operations are handle by the MDS. pNFS support is implemented as part of
+glusterFS+NFS-ganesha integration.
+
+### 1.) Pre-requisites
+
+  - Create a GlusterFS volume
+
+  - Install nfs-ganesha (refer section 5)
+
+  - Disable kernel-nfs, gluster-nfs services on the system using the following commands
+       - service nfs stop
+       - gluster vol set <volname> nfs.disable ON (Note: this command has to be repeated for all the volumes in the trusted-pool)
+
+### 2.) Configure nfs-ganesha for pNFS
+
+  - Disable nfs-ganesha and tear down HA cluster via gluster cli (pNFS did not need to disturb HA setup)
+       - gluster features.ganesha disable
+
+  - For the optimal working of pNFS, ganesha servers should run on every node in the trusted pool manually(refer section 5)
+       - *#ganesha.nfsd -f <location_of_nfs-ganesha.conf_file> -L <location_of_log_file> -N <log_level> -d*
+
+  - Check whether volume is exported via nfs-ganesha in all the nodes.
+       - *#showmount -e localhost*
+
+### 3.) Mount volume via pNFS
+
+Mount the volume using any nfs-ganesha server in the trusted pool.By default, nfs version 4.1 will use pNFS protocol for gluster volumes
+   - *#mount -t nfs4 -o minorversion=1 <ip of server>:/<volume name> <mount path>*
+
+### 4.) Points to be noted
+
+   - Current architecture supports only single MDS and mulitple DS. The server with which client mounts will act as MDS and all severs including MDS can act as DS.
+
+   - If any of the DS goes down , then MDS will handle those I/O's.
+
+   - Hereafter, all the subsequent nfs clients need to use same server for mounting that volume via pNFS. i.e more than one MDS for a volume is not prefered
+
+   - pNFS support is only tested with distributed, replicated or distribute-replicate volumes
+
+   - It is tested and verfied with RHEL 6.5 , fedora 20, fedora 21 nfs clients. It is always better to use latest nfs-clients
+
+### 5.) References
+
+   - Setup and create glusterfs volumes : http://www.gluster.org/community/documentation/index.php/QuickStart
+
+   - NFS-Ganesha wiki : https://github.com/nfs-ganesha/nfs-ganesha/wiki
+
+   - For installing, running NFS-Ganesha and exporting a volume :
+      - read doc/features/glusterfs_nfs-ganesha_integration.md
+      - http://blog.gluster.org/2014/09/glusterfs-and-nfs-ganesha-integration/