If you set a custom retention period for a snapshot, you can extend the period before the snapshot expires.
When a snapshot has 3 days left in its retention period, the Retention Period column in the snapshot list highlights the message Released After xx days.
Limits
You cannot extend the retention period of snapshots that are permanently retained.
You cannot extend the retention period of Cloud Backup snapshots in the ECS console. Instead, go to the Cloud Backup console and extend the retention period of a backup point.
You cannot extend the retention period of shared snapshots.
You cannot extend the retention period of archived snapshots.
You can only extend the retention period of a snapshot. You cannot shorten it.
Considerations
Alibaba Cloud charges standard snapshot storage fees in each region based on the snapshot size and retention period. Extending the retention period of a snapshot increases storage costs. For more information, see Snapshot billing.
If the Delete Automatic Snapshots While Releasing Disk attribute is enabled for a disk, its automatic snapshots are deleted when the disk is released, even if the snapshot retention period has not expired. A disk can be released manually, released with its instance, or released when you replace the operating system. For more information, see Enable the Delete Automatic Snapshots While Releasing Disk attribute.
Procedure
Go to ECS console - Snapshots.
In the top navigation bar, select the region and resource group of the resource that you want to manage.
On the Disk Snapshots tab, find the snapshot that you want to modify. Use one of the following methods to extend its retention period.
In the Actions column, choose .
In the Retention Period column, click the
icon.
Extend the retention period of the snapshot, and then click OK.

References
You can also call the ModifySnapshotAttribute API operation to extend the retention period of a snapshot.
To avoid unnecessary storage costs, periodically delete snapshots that you no longer need. For more information, see Delete a snapshot.
> Extend Retention Period