7.4 VTTS (Virtual tape transportation system)
The programs presented in this section are part of the VTTS (Virtual tape transportation system) and are
copyrighted and owned by Sam Golob, however the programs on CBTTAPE File #533 can be used
freely. The CBT MVS Utilities Tape (CBTTAPE) can be found at
File #533 of the CBT tape contains the following programs:
The VTT2TAPE program converts AWS-format tape files to real tapes, while the VTT2DISK program
creates an AWS-format virtual tape file from a real tape. The VTT2CNVU program converts a VB-format
AWS-format tape (such as the one produced by the AWSUTIL program) to FB-80 format on MVS so that
VTT2TAPE can be used subsequently to convert the data to a real tape.
The VTT2T2FK program is similar to VTT2DISK except that a real tape is converted to a FAKETAPE (tm)
format tape (see below). VTT2FK2T is similar to VTT2TAPE except that a FAKETAPE tape image, folded
over on MVS into FB-80 format, is converted into a real tape. Unless otherwise mentioned AWS-format
virtual tape files on an MVS system have been folded over into fixed blocked 80-byte record format.
AWS-format files on other systems are just long strings of data.
The FAKETAPE file format is a published interface of Fundamental Software Inc. Fundamental Software
reserves the right to change the format at any time. FAKETAPE and FLEX-ES are registered trademarks
of Fundamental Software Inc.
The AWS Tape format is produced by IBM's P/390 and Hercules systems to create disk files which an
MVS system reads and writes as if they were actual tapes. Another name for these disk files is "virtual
tapes", as the MVS system looking at these files "thinks" that they really are tapes.
There are programs like AWSUTIL which can read real tapes and create virtual tapes from them. These
virtual tapes can be loaded on a Hercules system somewhere and be read as a tape.
VTT2DISK performs this function also, by reading a real tape and producing an FB-80 folded AWS-format
tape as an MVS disk file. While reading the tape the VTT2DISK program produces a lot of statistics about
the tape. The advantage of the VTT2DISK program is that it can be run on mainframe-based MVS sys-
tems that cannot normally produce AWS-format virtual tapes.
Another issue is encountered when transferring data in the other direction. Suppose you have an MVS
system that cannot read a tape in AWS format. Most MVS systems which are not P/390 or Hercules
machines are in this position. For these you have to convert an AWS virtual tape disk file to some format
that the MVS system can convert into a REAL tape. That is the purpose of the VTT2TAPE program.
7.4.2 Control Statements
The VTT2DISK program allows the following keywords via the SYSIN DD Statement:
This specifies the chunksize. Any chunksize up to the limit of 65535 bytes is
allowed. If not specified the default is 65535 bytes.
This keyword changes the VOLSER on VOL1 label to volser.
The READ keyword produces a read only run, no AWSOUT is created.