Snapshots: Difference between revisions

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Snapshots are a implementation of [http://en.wikipedia.org/wiki/Copy-on-write| copy-on-write] that allows for a file system to quickly take a point-in-time copy of the file system and provide access to the data through a .snapshot directory. Snapshots provide a fast, user-accessible way to recover data that has been accidentally deleted or corrupted within a recent time window -- rather than having to retrieve the data from comparatively slow tape backups. They also help to span the time gap between full backups.
Snapshots are a implementation of [http://en.wikipedia.org/wiki/Copy-on-write| copy-on-write] that allows for a file system to quickly take a point-in-time copy of the file system and provide access to the data through a .snapshot directory. Snapshots provide a fast, user-accessible way to recover data that has been accidentally deleted or corrupted within a recent time window -- rather than having to retrieve the data from comparatively slow tape backups. They also help to span the time gap between full backups.


We provide [[Snapshots]] on our [[Snapshots:NetApp | NetApp]], [[SnapshotsNexenta | Nexenta]] and [[Snapshots:FluidFS | FluidFS]] filers to certain file systems.
We provide [[Snapshots]] on our [[Snapshots:NetApp | NetApp]], [[SnapshotsNexenta | Nexenta]] and [[Snapshots:FluidFS | FluidFS]] filers to certain file systems. If you are ever unsure if a particular volume has Snapshots enabled, please contact the [[HelpDesk | Help Desk]].
 
Please see [[SnapshotFileSystems]] for a list of our file systems that have snapshots in the department.


==Snapshot Policy==
==Snapshot Policy==
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We retain up to 8 hourly snapshots, 2 daily snapshots and 1 weekly snapshot.
We retain up to 8 hourly snapshots, 2 daily snapshots and 1 weekly snapshot.
The filesystems on which snapshots are available are listed on the [[SnapshotFileSystems]] page.


==Snapshot Restoring==
==Snapshot Restoring==

Revision as of 13:14, 13 March 2014

Snapshots are a implementation of copy-on-write that allows for a file system to quickly take a point-in-time copy of the file system and provide access to the data through a .snapshot directory. Snapshots provide a fast, user-accessible way to recover data that has been accidentally deleted or corrupted within a recent time window -- rather than having to retrieve the data from comparatively slow tape backups. They also help to span the time gap between full backups.

We provide Snapshots on our NetApp, Nexenta and FluidFS filers to certain file systems. If you are ever unsure if a particular volume has Snapshots enabled, please contact the Help Desk.

Snapshot Policy

Our core file systems in the department are on a 4 hour snapshot cycle. Snapshots are taken at,

12am 4am 8am 12pm 4pm 8pm

We retain up to 8 hourly snapshots, 2 daily snapshots and 1 weekly snapshot.

Snapshot Restoring

If you have deleted a file by mistake and you need to get it back, you can use the snapshots directory to recopy the file. This directory can typically be found in your home directory; it will be prepended by a ., so you will need to use the command "ls -a" to find it. It will be one of three:

The inside of one of these will look something like:

Screenshot-.snapshot - bash.png

For an example of file restoration, please see this page.