Saving to multiple devices to reduce your save window

Setting up saves to multiple devices

You can reduce your save window by using multiple devices. When you save to multiple devices you can use one of two techniques. You can issue a single save operation as one job, or you can issue multiple save operations as several jobs.

Single save operation

Save (or restore) operations identify a media file by the device (DEV), sequence number (SEQNBR), volume identifiers (VOL), and file label (LABEL) parameters. These parameters only allow one media file to be identified. However, a parallel save (or restore) operation uses more than one media file. You can solve this problem by using a media definition.

A media definition (*MEDDFN) allows you to identify more than one media file. A media definition defines the devices, sequence numbers, and volume identifiers that the parallel save operation will use.

A media definition also allows you to specify whether to save the data in parallel or serial format and whether to use dynamic device allocation.

You create a media definition by using the Create Media Definition (QsrCreateMediaDefinition (ILE) or QSRCRTMD (OPM)) API.

Multiple save operation

When you issue multiple save operations to save different sets of data to different media devices, you perform concurrent save operations. The following scenarios provide some examples of situations when you might want to perform concurrent saves within the integrated file system.

• Save the complete integrated file system structure and all user libraries concurrently:

  SAV  DEV('/QSYS.LIB/TAP01.DEVD') OBJ(('/*') ('/QSYS.LIB' *OMIT) ('/QDLS' *OMIT))
  SAVLIB  LIB(*ALLUSR) DEV(TAP02)

• Save separate unmounted user-defined file systems concurrently:

  SAV  DEV('/QSYS.LIB/TAP01.DEVD') OBJ(('/dev/udfs-directory/udfs-01.udfs')
  SAV  DEV('/QSYS.LIB/TAP02.DEVD') OBJ(('/dev/udfs-directory/udfs-02.udfs')