6. DATA SOURCES › 6.2 VTS Component Data Sources › 6.2.1 IBM VTS SMF Data › 6.2.1.1 SMF Type 94 Record Description

6.2.1.1 SMF Type 94 Record Description

The SMF Type 94 IBM Tape Library Dataserver Statistics record
predated IBM VTS virtual tape systems.  Originally, the
hourly record statistics generated by IBM 34xx Self Managed
tape libraries contained 128 bytes of data with information
about real tape drive activity in the tape library.

With the introduction of the IBM VTS, the record was expanded
to include an additional 128 bytes of data containing VTS-
related information.  Over time, the record was further
expanded to accommodate the peer-to-peer VTS and then to
provide improved DASD cache, physical drive, and physical
cartridge pool information.

Each SMF type 94 record subtype shows an hour's worth of VTS
activity and status information.  The statistics summarize
the interaction of all z/OS systems with the VTS.  There is
no breakdown of information at the individual z/OS system
level.

The SMF type 94 record is comprised of two subtypes:

Subtype 1         The subtype 1 record is always generated.
                  The basic record contains detailed
                  information about:

                  o Physical tape drive availability and
                    activity.  Statistics for physical
                    mounts, dismounts, ejects, audits,
                    inserts, and imports/exports.


                  o VTS data movement to and from z/OS
                    systems and DASD cache.  VTS data
                    movement to and from DASD cache and
                    physical cartridges.  Statistics for
                    physical and virtual mounts, DASD cache
                    and physical cartridge utilization
                    buckets.  Statistical buckets with counts
                    of data block movement by blocksize
                    ranges.  Statistics on various throttle
                    values and compression ratios.

                  o For peer-to-peer VTSs, statistics are
                    provided for each virtual tape controller
                    (AXn, up to eight) showing the copy mode,
                    data volume, virtual mounts, compression
                    ratios, and virtual volume copies
                    achieved.

                  When IBM F/C 4001 is installed and
                  available, the subtype 1 record contains
                  additional VTS information:

                  o A breakdown on physical tape device
                    activity by device type, for up to two
                    device types if multiple device types
                    are assigned to the VTS.

                  o A breakdown on VTS DASD cache utilization
                    by preference group, if preference groups
                    are used to prioritize one group of
                    virtual volumes over another.

Subtype 2         The subtype 2 record is only generated if
                  IBM F/C 4001 is installed and Outboard
                  Policy Management is enabled.

                  It provides information about each volume
                  pool associated with the VTS physical
                  cartridges.  For each volume pool, counts
                  are provided for scratch and used
                  cartridges.  Media types assigned to the
                  pool are identified.  For active
                  cartridges, 20 buckets are provided showing
                  how many cartridges are filled at each 5%
                  range.