Saving to multiple devices to reduce your save window

 

Use these save methods to decrease your save window by saving to multiple devices.

 

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 saves. The following scenarios provide some examples of situations when you may 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')

• Saving libraries to multiple devices for a single save operation
  You can perform a save operation while using more than one media device simultaneously.

• Saving the Integrated File System using multiple devices for a single save operation
  A traditional save to a single device produces one tape file on the tape media. You can perform a save operation while using more than one media devices simultaneously.

• Dynamic device allocation
  Dynamic device allocation allows you to allocate tape devices as they are needed.

• Restrictions for saving to multiple devices
  The devices that you specify in a media definition must be compatible standalone tape devices or tape media library devices.

 

Parent topic:

Considerations and restrictions for the save-while-active function

Related reference
Restrictions for saving to multiple devices