Moving or Copying of Datacom AD/DB Sequential files

Products

• Disk Backup and Restore - MVS
• DISK BACKUP AND RESTORE- ADD-ON OPTIO
• DISK BACKUP AND RESTORE

Issue/Introduction

Is it possible to use Disk™ Backup and Restore to move or copy Datacom AD/DB Sequential files?

Environment

Release: Disk™ Backup and Restore

Resolution

Only a track-image process can be used to move the Datacom AD/DB Seq. files. Disk™ Backup and Restore cannot be used for this because it processes data sets by the "logical block", and not by track-image.

The following explains this requirement from Datacom:

Sequential files used by Datacom/DB, including output of a BACKUP or input to a LOAD, are Operating System standard data sets. Datacom uses normal QSAM for writing and reading them.

Datacom/DB data sets including system areas CXX/LXX/FXX/WXX/PXX and data base areas IXX and Inn and Ann are totally different. They are written using a low level access method to write exactly what is needed where it is needed and are read the same. Information is placed on each track as the DASD hardware allows it to be placed and provides complete flexibility. What is on DASD is proprietary and will not be documented or explained.

As Datacom knows what it can write to DASD it knows how to properly read it. Therefore, if a data set is closed and it is 'moved' from one set of DASD to another, Datacom will have no problems or care if the data set is moved to a perfect duplicate image, including every byte of every track with nothing shifted, nothing deleted, nothing added.

Datacom does not support a change in DASD geometry. A data set allocated to a 3390 device must always reside on a 3390.

Datacom DOES support changes in extents and locations on the DASD. For example, a data set having 30 extents over 8 volumes may be changed to be 1 extent over 1 volume or the other way, to be 90 extents over 32 volumes. But again, this can only be done by the track-image process.