snapview-server: register a callback with glusterd to get notifications

* As of now snapview-server is polling (sending rpc requests to glusterd) to
  get the latest list of snapshots at some regular time intervals
  (non configurable). Instead of that register a callback with glusterd so that
  glusterd sends notifications to snapd whenever a snapshot is created/deleted
  and snapview-server can configure itself.

Change-Id: I17a274fd2ab487d030678f0077feb2b0f35e5896
BUG: 1119628
Signed-off-by: Raghavendra Bhat <raghavendra@redhat.com>
Reviewed-on: http://review.gluster.org/8150
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>

1 files changed, 47 insertions, 0 deletions

diff --git a/doc/admin-guide/en-US/markdown/admin_managing_snapshots.md b/doc/admin-guide/en-US/markdown/admin_managing_snapshots.md
index d79451c7437..3de64af56ef 100644
--- a/doc/admin-guide/en-US/markdown/admin_managing_snapshots.md
+++ b/doc/admin-guide/en-US/markdown/admin_managing_snapshots.md
@@ -160,3 +160,50 @@ Details:
 Deactivates the mentioned snapshot.
 
 -------------------------------------------------------------------------
+
+**Accessing the snapshot**
+
+Snapshots can be activated in 2 ways.
+
+1) Mounting the snapshot:
+
+The snapshot can be accessed via FUSE mount (only fuse). To do that it has to be
+mounted first. A snapshot can be mounted via fuse by below command
+
+*mount -t glusterfs <hostname>:/snaps/<snap-name>/<volume-name> <mount-path>*
+
+i.e. say "host1" is one of the peers. Let "vol" be the volume name and "my-snap"
+be the snapshot name. In this case a snapshot can be mounted via this command
+
+*mount -t glusterfs host1:/snaps/my-snap/vol /mnt/snapshot*
+
+
+2) User serviceability:
+
+Apart from the above method of mounting the snapshot, a list of available
+snapshots and the contents of each snapshot can be viewed from any of the mount
+points accessing the glusterfs volume (either FUSE or NFS or SMB). For having
+user serviceable snapshots, it has to be enabled for a volume first. User
+serviceability can be enabled for a volume using the below command.
+
+*gluster volume set <volname> features.uss enable*
+
+Once enabled, from any of the directory (including root of the filesystem) an
+access point will be created to the snapshot world. The access point is a hidden
+directory cding into which will make the user enter the snapshot world. By
+default the hidden directory is ".snaps". Once user serviceability is enabled,
+one will be able to cd into .snaps from any directory. Doing "ls" on that
+directory shows a list of directories which are nothing but the snapshots
+present for that volume. Say if there are 3 snapshots ("snap1", "snap2",
+"snap3"), then doing ls in .snaps directory will show those 3 names as the
+directory entries. They represent the state of the directory from which .snaps
+was entered, at different points in time.
+
+NOTE: The access to the snapshots are read-only.
+
+Also, the name of the hidden directory (or the access point to the snapshot
+world) can be changed using the below command.
+
+*gluster volume set <volname> snapshot-directory <new-name>*
+
+--------------------------------------------------------------------------------------