Tape mount management (TMM) is a methodology that is used to optimize tape subsystem operation and use. It consists of hardware and software facilities, which manage tape data efficiently. By using DFSMShsm in conjunction with your ACS routines to implement the TMM methodology, you can redirect multiple output data sets to DASD, then later have them moved to a single tape, with a single tape mount. This not only improves tape usage, but also greatly reduces the number of tape mounts that are required.
The following table illustrates the differences between normal interval migration processing and TMM processing:
| DFSMShsm Options or Controls | Interval Migration | TMM with SMS |
|---|---|---|
| Hourly option
Note: Hourly
migration is not performed on a host that is currently running primary
space management.
|
Storage group having AM=Y (Auto Migrate,
yes)
Note: Specifying AM=Y for a storage group requests
that primary space management and event-driven migration both be performed
on volumes in this storage group. An option of AM=P (Auto Migrate,
primary) indicates only primary space management is performed.
|
Storage group having
AM=I (Auto Migrate, interval)
Note: This option is referred
to as tape mount management (TMM).
|
| SETSYS INTERVALMIGRATION | Volumes meeting trigger threshold may be processed hourly on this host. | Volumes meeting trigger threshold may be processed hourly on this host. |
| SETSYS NOINTERVALMIGRATION | Volumes are not processed hourly on this host. | Volumes meeting trigger threshold may be processed hourly on this host. |
| Threshold range | 1–99 | 0–99 |
| Trigger threshold | High threshold | Midpoint between high and low threshold. |
| Max interval tasks of 0 | No hourly migration will be done
on this host.
Note: The option of NOINTERVALMIGRATION
provides the same capability for this category of data.
|
No hourly migration
will be done on this host.
Note: Be aware that if you
set the SETSYS MAXINTERVALTASKS parameter to zero, you are preventing
hourly migration for all storage groups and non-SMS volumes on this
host.
|
| Max interval tasks x | x tasks available to do hourly migration of volumes meeting trigger threshold. | x tasks available to do hourly migrations of volumes meeting trigger threshold. |
| AMHOST=blank | Hourly migration can be performed on any host permitting interval migration and having interval tasks. | Hourly migration can be performed on any host having interval tasks. |
| AMHOST=system or system group name
Note: If you want to allow hourly processing on more than one
host but not on all hosts of a sysplex, then you can specify the combination
of a sysplex restricting name and also specify SETSYS MAXINTERVALTASKS(0)
on the hosts where you do not want to permit hourly migration.
|
Primary space management and hourly migration limited to this system or group. | Primary space management and hourly migration limited to this system or group. |