Red Hat SummitChapter 8. Snapshot Basics
The following procedures demonstrate how to create, list, and remove snapshots using the rbd command on the command line.
8.1. Create Snapshot
To create a snapshot with rbd, specify the snap create option, the pool name and the image name:
rbd --pool {pool-name} snap create --snap {snap-name} {image-name}
rbd snap create {pool-name}/{image-name}@{snap-name}
rbd --pool {pool-name} snap create --snap {snap-name} {image-name}
rbd snap create {pool-name}/{image-name}@{snap-name}For example:
rbd --pool rbd snap create --snap snapname foo rbd snap create rbd/foo@snapname
rbd --pool rbd snap create --snap snapname foo
rbd snap create rbd/foo@snapname8.2. List Snapshots
To list snapshots of an image, specify the pool name and the image name:
rbd --pool {pool-name} snap ls {image-name}
rbd snap ls {pool-name}/{image-name}
rbd --pool {pool-name} snap ls {image-name}
rbd snap ls {pool-name}/{image-name}For example:
rbd --pool rbd snap ls foo rbd snap ls rbd/foo
rbd --pool rbd snap ls foo
rbd snap ls rbd/foo8.3. Rollback Snapshot
To rollback to a snapshot with rbd, specify the snap rollback option, the pool name, the image name and the snap name:
rbd --pool {pool-name} snap rollback --snap {snap-name} {image-name}
rbd snap rollback {pool-name}/{image-name}@{snap-name}
rbd --pool {pool-name} snap rollback --snap {snap-name} {image-name}
rbd snap rollback {pool-name}/{image-name}@{snap-name}For example:
rbd --pool rbd snap rollback --snap snapname foo rbd snap rollback rbd/foo@snapname
rbd --pool rbd snap rollback --snap snapname foo
rbd snap rollback rbd/foo@snapnameRolling back an image to a snapshot means overwriting the current version of the image with data from a snapshot. The time it takes to execute a rollback increases with the size of the image. It is faster to clone from a snapshot than to rollback an image to a snapshot, and it is the preferred method of returning to a pre-existing state.
8.4. Delete a Snapshot
To delete a snapshot with rbd, specify the snap rm option, the pool name, the image name and the username:
rbd --pool {pool-name} snap rm --snap {snap-name} {image-name}
rbd snap rm {pool-name}/{image-name}@{snap-name}
rbd --pool {pool-name} snap rm --snap {snap-name} {image-name}
rbd snap rm {pool-name}/{image-name}@{snap-name}For example:
rbd --pool rbd snap rm --snap snapname foo rbd snap rm rbd/foo@snapname
rbd --pool rbd snap rm --snap snapname foo
rbd snap rm rbd/foo@snapnameCeph OSDs delete data asynchronously, so deleting a snapshot doesn’t free up the disk space immediately.
8.5. Purge Snapshots
To delete all snapshots for an image with rbd, specify the snap purge option and the image name:
rbd --pool {pool-name} snap purge {image-name}
rbd snap purge {pool-name}/{image-name}
rbd --pool {pool-name} snap purge {image-name}
rbd snap purge {pool-name}/{image-name}For example:
rbd --pool rbd snap purge foo rbd snap purge rbd/foo
rbd --pool rbd snap purge foo
rbd snap purge rbd/foo
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