-
Notifications
You must be signed in to change notification settings - Fork 0
New issue
Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.
By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.
Already on GitHub? Sign in to your account
Support snapshot merge / rollback in Stratis #597
Comments
This could be broken down into three separate tasks, which could be done in the order listed:
A consideration is the XFS filesystem UUID. It would have to be updated by the merge, which in some cases could be expensive. |
Filed #643 for the origin tracking and reporting parts. |
Closing, but leaving the sub-issues, to help track the port back from the patch branch. |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
The LVM2 project provides the capability to "merge" a snapshot volume back into its origin (the device from which the snapshot was originally created). Following the merge operation the content of the origin reflects the state at the point in time time the snapshot was created. This is useful to allow the file system state to be rolled back to an earlier point in time, for e.g. to recover from a failed update or other change scenario.
With device-mapper thin snapshots the merge operation is achieved by changing the mapping from device names to thin identifiers tracked by the pool, for example if
fs1
is some file system from which a snapshot,fs1-snap
was previously taken:Merging a stopped file system can proceed immediately since the volume is not in use. For active volumes a note must be made in the device metadata indicating the intent to merge which is then applied the next time the file system is started (for e.g. following a reboot).
Stratis currently has the ability to take snapshots of file systems but does not yet support automatically merging or rolling back a file system to an earlier state tracked by a snapshot. A similar result can be achieved by deleting or renaming the origin device and then renaming the snapshot with the old origin name but this is a manual process with a number of drawbacks:
Automating this process is particularly valuable for snapshots involving the root file system, since the manual approach would require the use of rescue media in order to de-activate, remove and replace the device containing the root file system.
The text was updated successfully, but these errors were encountered: