An online snapshot can be accessed by hosts. Set a snapshot offline to ensure that no hosts can access the snapshot. If a snapshot was online and you set it offline, any iSCSI connections to the snapshot will be lost.
Notes: If you allow a host to write to a snapshot, you can no longer be certain that the snapshot represents the volume data at the time the snapshot was created. If you set a snapshot online, set its permission to read-only.
To set a snapshot online, click:
Volumes > volume_name > snapshot_timestamp > Set snapshot online
To set a snapshot offline, click:
Volumes > volume_name > snapshot_timestamp > Set snapshot offline