Understanding multiplexing

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Multiplexing uses parallel access points to data on the database server. This configuration is useful when tape drives are used during database backup operations on the backup server.

This graphic shows the principle of multiplexing. On the left side of the graphic, the database server allows parallel access to the database. The network and the IBM Storage Protect server are not affected. — Figure 1. Multiplexing

This feature is provided by the PARALLELISM parameter available with the BACKUP DATABASE and RESTORE DATABASE commands. Refer to your DB2® Command Reference for details about these commands and the PARALLELISM parameter.

The value of keyword MULTIPLEXING defines the number of files that are read in parallel within a single session. Appropriate MULTIPLEXING values are expected in the range of 1 to 4. The best value for your environment depends on the I/O rate of your disks, the location of your data on the disks, the network capacity, the throughput rate of the storage media, and the compression setting. If the MULTIPLEXING value is too high, the processing that occurs might offset any performance gain.