Next tip will be published 23. april. Næste tip udkommer den 23. april.

The most irritating thing about IBM mainframes is that the datasets can run out of space. They always do at the most inconvenient moments. But you can get rid of the out of space condition in a reasonable easy way.

SMS has a utitily progam called ADRDSSU. Among a lot of things it is able to move datasets from one volume to another and it does it pretty fast. ADRDSSU moves datasets by allocating a new dataset on the target volume and copies the contens of the original dataset to this new dataset. After copying, it deletes the original and renames the new dataset to the name of the original dataset. The smart part is, that the new dataset is allocated big enough to hold all data of the original in one extent. The new dataset is then able to extent as many times as the dataset allocation and type allows.

ADRDSSU works in this fashion for both VSAM and NONVSAM datasets. You must have RACF ALTER authorization to move a dataset. You also need to know the name of the volume where the dataset is allocated, because you have to tell ADRDSSU a volume you want to move the dataset to. You can easily move the dataset to the same volume where it resided before the move.

The following piece of JCL shows how to move MY.OWN.DATASET allocated on volume MYDISK:

//ADRDSSU  EXEC PGM=ADRDSSU
//SYSPRINT DD SYSOUT=*
//SYSIN    DD *
    COPY -
    DATASET(INCLUDE(MY.OWN.DATASET)) -
    OUTDYNAM(MYDISK) DELETE CATALOG
/*

DB2-tablespaces are stored in VSAM-datasets. Therefore you can use ADRDSSU to perform a "REORG" of a DB2-tablespace. You can read about this in danish by clicking here. Otherwise you will have to wait about a year for this tip to be published in english. Warning: using ADRDSSU to perform "REORG" of a DB2-tablespace has nothing to do with a DB2 REORG.

You can read more about ADRDSSU in DFSMSdss Storage Administration Reference. This is not one of the best manuals, that IBM has written. If you feel a bit lost you are not alone.