The device selection attributes of a tape volume are recorded in
the TDSI fields of the tape volume record. The TDSI fields are set
when a tape cartridge is entered into a library. Your installation
should provide a cartridge entry installation exit to assist in the
process of setting the TDSI fields. See
Cartridge entry installation exit (CBRUXENT) for
more information concerning this cartridge entry installation exit.
See
TDSI coexistence considerations for more information
on TDSI. The following tape device selection information is assigned
to the tape volume:
- Recording technique-specified as UNKNOWN, 18TRACK, 36TRACK, 128TRACK,
256TRACK, 384TRACK, EFMT1, EFMT2, EEFMT2, EFMT3, EEFMT3, EFMT4, or
EEFMT4.
- Media type-specified as UNKNOWN, MEDIA1, MEDIA2, MEDIA3, MEDIA4,
MEDIA5, MEDIA6, MEDIA7, MEDIA8, MEDIA9, MEDIA10, MEDIA11, MEDIA12,
or MEDIA13.
- Compaction-specified as UNKNOWN, NONE, or COMPACTED.
- Special attribute-can be set to NONE or READCOMPATIBLE.
- 3490 read-compatibility processing
- 3490 read-compatibility processing allows a MEDIA1 cartridge written
on a base 3490 device using 18-track recording technique to be mounted
and read on a 3490E device. Data originally written to a volume using
a base 3490 can be overwritten using a 3490E device as long as the
recording starts at the load point of the volume. However, using a
3490E device to write additional data starting in the middle of a
volume originally written by a base 3490 is not permitted, since this
intermixes the 18-track and 36-track recording techniques on the same
volume.
In a nonlibrary environment, the allocation process provides two
system-defined esoteric unit names—SYS3480R and SYS348XR—that
allow the installation to specify that the volume is used for read-only
purposes so that 3490E drives become eligible for allocation.
- 3590 Model E read-compatibility processing
3590 Model E read-compatibility processing allows a MEDIA3 or MEDIA4
cartridge written on a 3590 Model B using the 128-track recording
technique to be mounted and read on a 3590 Model E. Data originally
written to a volume using a 3590 Model B can be overwritten using
a 3590 Model E as long as the recording starts at the load point of
the volume. However, using the 3590 Model E to write additional data
starting in the middle of a volume originally written by a 3590 Model
B is not permitted, because this intermixes the 128-track and 256-track
recording techniques on the same volume.
- 3590 Model H read-compatibility processing
3590 Model H read-compatibility processing allows a MEDIA3 or MEDIA4
cartridge written on a 3590 Model B tape drive using the 128-track
recording technique or a cartridge written on a 3590 Model E tape
drive using the 256-track recording technique to be mounted and read
on a 3590 Model H tape drive. Data that was originally written to
a volume using a 3590 Model B or Model E tape drive can be overwritten
using a 3590 Model H tape drive as long as the recording starts at
the load point of the volume. However, using the 3590 Model H tape
drive to write additional data starting in the middle of a volume
originally written by a 3590 Model B or Model E tape drive is not
permitted, because this intermixes the recording techniques on the
same volume.
- 3592 Model E05 read-compatibility processing
Because the 3592 Model E05 is downward read and write compatible
with the EFMT1 format, explicit specification of the read-compatible
special attribute indicator (TDSSPEC) or usage of the LABEL=(,,,IN)
on the DD statement of JCL, is not required for an EFMT1 formatted
cartridge to be read on a 3592 Model E05.
- 3592 Model E06 read-compatibility processing
- Because the 3592 Model E06 is only downward read compatible with
the EFMT1 format, explicit specification of the read-compatible special
attribute indicator (TDSSPEC) or usage of the LABEL=(,,,IN) on the
DD statement of JCL is required for the 3592 Model E06 to be considered
eligible for an EFMT1 read request. Furthermore, because the 3592
Model E06 can read and write the EFMT2 and EEFMT2 recording formats,
no read-compatible considerations are needed for the EFMT2 or EEFMT2
formats.
- 3592 Model E07 read-compatibility processing
- The 3592 Model E07 is only downward read (and not write) compatible
with:
- EFMT1 format on MEDIA5 through MEDIA8.
- EFMT2 and EEFMT2 formats on MEDIA5 through MEDIA10.
- EFMT3 and EEFMT3 formats on MEDIA5 through MEDIA8.
Explicit specification of the read-compatible special attribute
indicator (TDSSPEC) or usage of the LABEL=(,,,IN) on the DD statement
of JCL is required for the 3592 Model E07 to be considered eligible
to read a volume recorded in these formats.
In a nonlibrary environment, there are no equivalent 3590 system-defined
esoteric unit names.
For a request for an SMS-managed volume, the JCL UNIT specification
is ignored, so read-compatibility must be managed in a different manner.
There is a read-compatible special attribute indicator in the TDSI
that can be set for a read-only request. This enables tape drives
that provide read-only support for a particular recording format to
be eligible for a read-only request. Your installation is responsible
to set the read-compatible special attribute in either of the following
manners:
- Using the cartridge entry installation exit (CBRUXENT).
- Using the LCS external services CUA function.
- Using the access method services ALTER VOLUMEENTRY service. (For
more information on access method services, see z/OS DFSMS Access Method Services Commands.)
Once the attribute is set, it remains set until the volume is returned
to scratch. To request read-compatibility for a single usage of the
volume, you can specify LABEL=(,,,IN) on the DD statement of
your JCL.