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Diffstat (limited to 'doc')
| -rw-r--r-- | doc/admin-guide/en-US/markdown/admin_managing_snapshots.md | 36 |
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 3de64af56ef..add2aad8fb5 100644 --- a/doc/admin-guide/en-US/markdown/admin_managing_snapshots.md +++ b/doc/admin-guide/en-US/markdown/admin_managing_snapshots.md @@ -14,6 +14,42 @@ 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. + + +Few features of snapshot are: +============================= + +**Crash Consistency** + +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. + + +**Online Snapshot** + +When the snapshot is being taken the file system and its associated data +continue to be available for the clients. + + +**Quorum Based** + +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. + + +**Barrier** + +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. + Snapshot Management |