gluster: GlusterFS Volume Snapshot Feature

This is the initial patch for the Snapshot feature. Current patch
includes following features:
* Snapshot create
* Snapshot delete
* Snapshot restore
* Snapshot list
* Snapshot info
* Snapshot status
* Snapshot config

Change-Id: I2f46920c0d61c515f6a60e0f8b46fff886d9f6a9
BUG: 1061685
Signed-off-by: shishir gowda <sgowda@redhat.com>
Signed-off-by: Sachin Pandit <spandit@redhat.com>
Signed-off-by: Vijaikumar M <vmallika@redhat.com>
Signed-off-by: Raghavendra Bhat <raghavendra@redhat.com>
Signed-off-by: Rajesh Joseph <rjoseph@redhat.com>
Signed-off-by: Joseph Fernandes <josferna@redhat.com>
Signed-off-by: Avra Sengupta <asengupt@redhat.com>
Reviewed-on: http://review.gluster.org/7128
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>

1 files changed, 66 insertions, 0 deletions

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+Managing GlusterFS Volume Snapshots
+==========================
+
+This section describes how to perform common GlusterFS volume snapshot
+management operations
+
+Pre-requisites
+=====================
+
+GlusterFS volume snapshot feature is based on thinly provisioned LVM snapshot.
+To make use of snapshot feature GlusterFS volume should fulfill following
+pre-requisites:
+
+* Each brick should be on an independent thinly provisioned LVM.
+* Brick LVM should not contain any other data other than brick.
+* None of the brick should be on a thick LVM.
+
+
+Snapshot Management
+=====================
+
+
+**Snapshot creation**
+
+*gluster snapshot create \<vol-name\> \[-n \<snap-name\>\] \[-d \<description\>\]*
+
+This command will create a snapshot of a GlusterFS volume. User can provide a snap-name and a description to identify the snap. The description cannot be more than 1024 characters.
+
+Volume should be present and it should be in started state.
+
+**Restoring snaps**
+
+*gluster snapshot restore -v \<vol-name\> \<snap-name\>*
+
+This command restores an already taken snapshot of a GlusterFS volume. Snapshot restore is an offline activity therefore if the volume is online then the restore operation will fail.
+
+Once the snapshot is restored  it will be deleted from the list of snapshot.
+
+**Deleting snaps**
+
+*gluster snapshot delete \<volname\>\ -s \<snap-name\> \[force\]*
+
+This command will delete the specified snapshot.
+
+**Listing of available snaps**
+
+*gluster snapshot list \[\<volname\> \[-s \<snap-name>\]\]*
+
+This command is used to list all snapshots taken, or for a specified volume. If snap-name is provided then it will list the details of that snap.
+
+**Configuring the snapshot behavior**
+
+*gluster snapshot config \[\<vol-name | all\>\]*
+
+This command will display existing config values for a volume. If volume name is not provided then config values of all the volume is displayed. System config is displayed irrespective of volume name.
+
+*gluster snapshot config \<vol-name | all\> \[\<snap-max-hard-limit\> \<count\>\] \[\<snap-max-soft-limit\> \<percentage\>\]*
+
+The above command can be used to change the existing config values. If vol-name is provided then config value of that volume is changed, else it will set/change the system limit.
+
+The system limit is the default value of the config for all the volume. Volume specific limit cannot cross the system limit. If a volume specific limit is not provided then system limit will be considered.
+
+If any of this limit is decreased and the current snap count of the system/volume is more than the limit then the command will fail. If user still want to decrease the limit then force option should be used.
+
+
+