etag
etag
is used for optimistic concurrency control as a way to help prevent simultaneous updates of a backup from overwriting each other. It is strongly suggested that systems make use of the etag
in the read-modify-write cycle to perform backup updates in order to avoid race conditions: An etag
is returned in the response to GetBackup
, and systems are expected to put that etag in the request to UpdateBackup
or DeleteBackup
to ensure that their change will be applied to the same version of the resource.