Free pool

Every tape, regardless of whether it is free or reserved, is connected to a free pool. If it is free, then it is located in this free pool. If it is reserved, it is assigned to this free pool when it is released. MAREN knows and manages all free pools by means of their names in the MAREN catalog. Even a free tape pool that does not contain any free tapes may still be needed later. If no tapes reference this pool name, the administration block can be deleted (MARENADM statement MODIFY-MAREN-PARAMETERS FREE-POOLS=*PARAMETERS(FREE-POOL=...,ACTION=*REMOVE). Deletion can only be performed explicitly by the All-Domain Administrator (ADA).

When a free tape is requested, a free tape pool is found that can be used to meet the demand. If there hasn't a suitable free tape , the operating staff is requested to make a suitable tape available in this free pool.

The MAREN free pool can be roughly split up into two areas:

• free tapes prereserved for HSMS/ARCHIVE applications (FREE-POOL=*TSOS/*GLOBAL/<dir-name>);
• in pools for free tapes for applications that are not specified (FREE-POOL=*NO), e.g. for requests via the command CREATE-FILE.

Free tapes for HSMS/ARCHIVE applications can only be reserved in the course of an HSMS/ARCHIVE run. Depending on their allocation, they can be split up into the following groups:

• Tapes prereserved for HSMS/ARCHIVE applications in a specific directory (<dir-name> tape pool).
• Tapes prereserved for HSMS/ARCHIVE applications under the TSOS user ID (TSOS tape pool).
• Tapes prereserved for all other HSMS/ARCHIVE applications (GLOBAL tape pool).

See also the section “HSMS/ARCHIVE free tape pools in the MAREN catalog”.

Tapes of the pools *TSOS/<dir-name> are reservered for HSMS/ARCHIVE applications. *GLOBAL tapes cannot only be used by ARCHIVE, but also by other applications.

Examples of how free pools are operated are provided on "Operating free tape pools".

A tape’s allocation determines its location after it has been processed with HSMS/ARCHIVE. Tape reservation in HSMS/ARCHIVE is closely linked with MARENUCP automatic free tape allocation.

When HSMS/ARCHIVE requests a tape, MAREN will search for an appropriate volume using the following criteria in the order given below:

1. If a request is received for a specific directory, a tape is reserved that was prereserved for that specific directory (FREE-POOL=<dir-name>).
2. If a request is received from an HSMS/ARCHIVE application running under the TSOS user ID and if there is no free tape pool for the specified directory, then a tape is reserved that is prereserved for HSMS/ARCHIVE applications running under TSOS (FREE-POOL=*TSOS). The free pool *TSOS is selected only if the user ID TSOS is the directory owner.
3. A tape is reserved that was prereserved for optional HSMS/ARCHIVE applications (FREE-POOL= *GLOBAL) under the following conditions: A request is received from any other HSMS/ARCHIVE application respectively HSMS/ARCHIVE is running and the owner of the directories is not TSOS and no free pool exists for the specified directory.
4. In all other cases, a free tape is taken from the free tape pool that has no reservations for HSMS/ARCHIVE (FREE-POOL=*NO).

The tapes can only be released following a PURGE run in ARCHIVE.

The MARENADM statement FREE-VOLUMES returns the tapes to the free pool assigned to them. Assignment to the free pools can take place with the ADD-FREE-VOLUMES and MODIFY-VOLUME-ATTRIBUTES statements.