1. Administrator's Guide
  2. Library Performance
  3. Minimizing Pass-Thru Activity Using ACSAPI Requests and ACSLS Commands

Minimizing Pass-Thru Activity Using ACSAPI Requests and ACSLS Commands

These ACSAPI requests and ACSLS cmd_proc commands can help you avoid unnecessary pass-thru activity between LSMs.

The following applies to both ACSAPI requests from a client to ACSLS, and to ACSLS commands entered using cmd_proc. The term “request" is used for both ACSAPI requests and cmd_proc commands.

Mounting a Specific Cartridge

This applies to either mounting a data cartridge or a specific scratch (empty) cartridge that you selected. Use the following commands:

  • query mount

  • mount

query mount

  • For a specified cartridge (vol_id), return a list of drives that are compatible with the cartridge's media type, ordered by proximity to the cartridge. (The compatible drives in the closest LSM are listed first, and so forth.)

  • With ACSLS 7.3 and later releases, drives that are the same pass-thru distance from the cartridge are in least-recently-used order.

    Example: The compatible drive within the cartridge's LSM with the longest time since a cartridge was dismounted, is first; the drive with the next longest time, is second, and so on.

Command: query mount vol_id

mount

Mount your specific cartridge, selecting an available (not in-use) drive from as close to the top of the list as possible.

Mounting a Scratch Cartridge Selected by ACSLS

The following section discusses mounting a scratch cartridge selected by ACSLS.

query mount scratch (also known as query mount *)

For a specified scratch pool, a list of all drives compatible with the media type(s) of the cartridges in a specified scratch pool is returned. A specific media type can be specified to restrict the drives to only those compatible with the specified media type.

The list of drives returned is ordered so that the drives closest to the densest scratch pools are listed first.

Command:

  • ACSAPI

  • cmd_proc

  • query mount scratch

    query mount * pool_id [media media_type]

Either a specific media type or ALL_MEDIA_TYPE (media * in a cmd_proc command) can be specified. ANY_MEDIA_TYPE is not supported.

Note:

When ALL_MEDIA_TYPE is specified, cartridges with media compatible with the drive are selected to determine the densest scratch pool.

mount scratch (also known as query mount *)

For a specified drive, select a scratch (empty) cartridge and mount it. Optionally, select the cartridge from a specified scratch pool and/or with a specified media type. ACSLS selects a compatible scratch cartridge in the closest LSM to the drive. In order to rotate use among all cartridges, the compatible cartridge with the least recent access date is selected within the selected LSM.

Command: 

  • ACSAPI
cmd_proc
mount scratch
mount * drive_id [pool_id] [media media_type]

  • For an ACSAPI request, drive_id, pool_id and media_type must be specified. (Either a specific media type, ALL_MEDIA_TYPE, or ANY_MEDIA_TYPE can be specified for media_type.)

  • With a cmd_proc mount * command, if pool_id is not specified, it defaults to the common pool (pool 0).

    A specific media type can be identified. If media * is specified, ANY_MEDIA_TYPE is chosen. If media is not specified, ALL_MEDIA_TYPE is chosen.

The special media_type values of ANY_MEDIA_TYPE and ALL_MEDIA_TYPE are processed, as follows:

  • When ALL_MEDIA_TYPE is specified, a cartridge with a media type compatible with the drive is selected. (This is based on the media_compatibility file.)

  • When ANY_MEDIA_TYPE is specified, the scratch_preferences file identifies the preferred list of media to mount on a drive.