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Chapter 21. Using snapshots on Stratis file systems

You can use snapshots on Stratis file systems to capture file system state at arbitrary times and restore it in the future.

Important

Stratis is a Technology Preview feature only. Technology Preview features are not supported with Red Hat production service level agreements (SLAs) and might not be functionally complete. Red Hat does not recommend using them in production. These features provide early access to upcoming product features, enabling customers to test functionality and provide feedback during the development process. For more information about the support scope of Red Hat Technology Preview features, see https://access.redhat.com/support/offerings/techpreview.

21.1. Characteristics of Stratis snapshots

This section describes the properties and limitations of file system snapshots on Stratis.

In Stratis, a snapshot is a regular Stratis file system created as a copy of another Stratis file system. The snapshot initially contains the same file content as the original file system, but can change as the snapshot is modified. Whatever changes you make to the snapshot will not be reflected in the original file system.

The current snapshot implementation in Stratis is characterized by the following:

  • A snapshot of a file system is another file system.
  • A snapshot and its origin are not linked in lifetime. A snapshotted file system can live longer than the file system it was created from.
  • A file system does not have to be mounted to create a snapshot from it.
  • Each snapshot uses around half a gigabyte of actual backing storage, which is needed for the XFS log.

21.2. Creating a Stratis snapshot

This procedure creates a Stratis file system as a snapshot of an existing Stratis file system.

Prerequisites

Procedure

  • To create a Stratis snapshot, use:

    # stratis fs snapshot my-pool my-fs my-fs-snapshot

Additional resources

  • stratis(8) man page.

21.3. Accessing the content of a Stratis snapshot

This procedure mounts a snapshot of a Stratis file system to make it accessible for read and write operations.

Prerequisites

Procedure

  • To access the snapshot, mount it as a regular file system from the /dev/stratis/my-pool/ directory:

    # mount /dev/stratis/my-pool/my-fs-snapshot mount-point

Additional resources

21.4. Reverting a Stratis file system to a previous snapshot

This procedure reverts the content of a Stratis file system to the state captured in a Stratis snapshot.

Prerequisites

Procedure

  1. Optionally, back up the current state of the file system to be able to access it later:

    # stratis filesystem snapshot my-pool my-fs my-fs-backup
  2. Unmount and remove the original file system:

    # umount /dev/stratis/my-pool/my-fs
    # stratis filesystem destroy my-pool my-fs
  3. Create a copy of the snapshot under the name of the original file system:

    # stratis filesystem snapshot my-pool my-fs-snapshot my-fs
  4. Mount the snapshot, which is now accessible with the same name as the original file system:

    # mount /dev/stratis/my-pool/my-fs mount-point

The content of the file system named my-fs is now identical to the snapshot my-fs-snapshot.

Additional resources

  • stratis(8) man page.

21.5. Removing a Stratis snapshot

This procedure removes a Stratis snapshot from a pool. Data on the snapshot are lost.

Prerequisites

Procedure

  1. Unmount the snapshot:

    # umount /dev/stratis/my-pool/my-fs-snapshot
  2. Destroy the snapshot:

    # stratis filesystem destroy my-pool my-fs-snapshot

Additional resources

  • stratis(8) man page.

21.6. Additional resources