Hitachi MP-96RD625-01 manual URz Delta Resync Operation

•Journal data stored in the restore journal volume

The journal data is read from the restore journal volume to cache. The journal data that is read to cache is copied to the existing cache track and promoted to formal data. After that, the space for the restore journal volume is released.

URz Delta Resync Operation

When you are using URz and TCz Synchronous in a 3DC multi-target configuration, URz provides delta resync operation as one of the solutions for failures in primary site. In a 3DC multi-target configuration, there are one primary site and two secondary sites; TCz Synchronous and URz secondary sites. For detailed information about 3DC multi-target configuration, see section TCz Synchronous (3DC Multi-target Configuration).

If a failure occurs on the primary site in 3DC multi-target configuration, you need to use Business Continuity Manager to use the TCz Synchronous secondary site as the primary site. If you perform a delta resync operation after the TCz Synchronous secondary site becomes a primary site. The URz pair will be restored quickly by the delta resync operation, you will not need to wait for a long time before you can use the URz data volumes again.

Delta resync operation consists of the two processes; one is the process for the preparation before the failure occurs, the other is the process for the recovery after the failure occurs.

•Processing for the preparation before the failure occurs (see the next section)

•Processing for the recovery after the failure occurs (see section Switching the Master Journal Group of URz)

Journal Obtain in TCz Synchronous Secondary Site

To perform delta resync operation when a failure occurs, you also need to obtain the journal data in the TCz Synchronous secondary site of 3DC multi- target configuration. Specify the TCz Synchronous R-VOL in TCz Synchronous secondary site as the primary data volume, and specify the data volume in URz secondary site as the secondary data volume, in order to create a URz pair for the delta resync operation.

When you create a URz pair for delta resync operation, the differential data of data volumes in TCz Synchronous primary site and secondary site will be stored in the journal volumes in TCz Synchronous secondary site as journal data. The following figure shows an example.

2-28 Chapter 3 Preparing for Universal Replicator z/OS Operations

Hitachi Universal Replicator for IBM /OS User’s Guide