Operational Considerations › High-Speed Open (HSOPEN) Option

High-Speed Open (HSOPEN) Option

When the High-Speed Open (HSOPEN) option is activated, the starting block ID of each Virtual Volume stacked on a Backstore Tape is saved in the OWNER field of the catalog entry for the stacked Virtual Volume (PREFIX.VVE.Vvolser.PRIMARY/DUPLEX) by Externalization and Recycle. Recall, Externalization, and Recycle retrieves the Backstore Tape catalog entry and use the owner field value is to quickly position the tape to the start of the Virtual Volume data set that needs to be read.

When HSOPEN is deactivated, the starting block ID of each Virtual Volume stacked on a Backstore Tape is not saved. When Recall, Externalization, or Recycle mount a Backstore Tape, open processing must forward space through the cartridge to find the required Virtual Volume data set. Significant delays can be seen depending on where the required Virtual Volume data set is located on the Backstore Tape.

The OWNER field in catalog entries is normally not used. If your site uses the OWNER field, you must deactivate the HSOPEN option until you determine if CA Vtape can be exempted from your OWNER field processing.

The value set for the HSOPEN option is saved in the Local VCAT. The value remains in effect across IPLs until it is changed or a new Local VCAT is created. When a new Local VCAT is defined, HSOPEN is automatically turned on. When a new Local VCAT is defined, HSOPEN is automatically turned on.

Because the setting is in the Local VCAT, it is unique to each CA Vtape subsystem. To activate or deactivate HSOPEN, you must issue the SVTn SET HSOPEN= console command for each active subsystem that will be performing Externalization or communicating with a Recycle Job.

You can determine the current setting by executing the SVTn Display Status console command for each active subsystem.

Note: The SVTn SET HSOPEN= console command was added to the sample VTSCMDS (Startup Commands) parmlib member to ensure that the High-Speed Open option is always set to the appropriate value when CA Vtape is started. The default value is ON. If the OWNER field cannot be used at your site, you will need to change this to OFF.