Abstract: The TS7700 Release 2.1 code added a flavor of immediate copy called Synchronous Mode Copy (SMC). With SMC, two copies of a logical volume are written at the same time to two clusters in a grid. When an explicit or implicit tape sync operation occurs the TS7700 grid ensures that the data written into the device buffer so far has also been written to each TS7700’s disk cache before the response to the tape operation is returned. Synchronous mode copy is a form of replication similar to host-initiated duplexing that can provide a zero recovery point objective (RPO) for sets of records (datasets) or byte-stream data (objects) written to virtual tape.
Version 1.1 of this paper includes the Time Delayed Copy Policy introduced in TS7700 R3.1, and the Private Mount option (Dual open for MOD) introduced in TS7700 R3.2. It has been reposted with revision marks included.