|author||Sachin Pandit <email@example.com>||2014-09-23 07:03:11 +0530|
|committer||Vijay Bellur <firstname.lastname@example.org>||2014-09-23 10:23:56 -0700|
doc/snapshot : admin guide updation.
Change-Id: I1980bc0984f941cd415fbc754495353f561155a8 BUG: 1145069 Signed-off-by: Sachin Pandit <email@example.com> Reviewed-on: http://review.gluster.org/8817 Tested-by: Gluster Build System <firstname.lastname@example.org> Reviewed-by: Vijay Bellur <email@example.com>
Diffstat (limited to 'doc/admin-guide/en-US')
1 files changed, 36 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 5618a4d9cdb..93be39d94d5 100644
@@ -14,11 +14,47 @@ 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.
+* gluster version should be 3.6 and above.
Details of how to create thin volume can be found at the following link.
+Few features of snapshot are:
+when a snapshot is taken at a particular point-in-time, it is made sure that
+the taken snapshot is crash consistent. when the taken snapshot is restored,
+then the data is identical as it was at the time of taking a snapshot.
+When the snapshot is being taken the file system and its associated data
+continue to be available for the clients.
+The quorum feature ensures that the volume is in good condition while the bricks
+are down. Quorum is not met if any bricks are down in a n-way replication where
+n <= 2. Quorum is met when m bricks are up, where m >= (n/2 + 1) where n is odd,
+and m >= n/2 and first brick is up where n is even. snapshot creation fails
+if quorum is not met.
+During snapshot creation some of the fops are blocked to guarantee crash
+consistency. There is a default time-out of 2 minutes, if snapshot creation
+is not complete within that span then fops are unbarried. If unbarrier happens
+before the snapshot creation is complete then the snapshot creation operation
+fails. This to ensure that the snapshot is in a consistent state.