Decreasing the size of a compatibility mode aggregate

You can decrease the size of a zFS aggregate using the pax command. Figure 1 shows a sample job.

Figure 1. Sample job to decrease the size of an aggregate

//SUIMGVMB JOB ,'SHRINK AGGR WITH PAX',
//         CLASS=A,MSGCLASS=X,MSGLEVEL=(1,1)
//* Make sure you have no line numbers in this JCL
//DEFINE   EXEC   PGM=IDCAMS
//SYSPRINT DD     SYSOUT=H
//SYSIN    DD     *
     DEFINE CLUSTER (NAME(PLEX.NEW.AGGR002.LDS0002) -
            LINEAR CYL(25 5) SHAREOPTIONS(3) -
            VOLUMES(CFC000 CFC001))
/*
//FORMAT   EXEC   PGM=IOEAGFMT,REGION=0M,
//* On the next line, aggregate and compat must be lower case
// PARM=('-aggregate PLEX.NEW.AGGR002.LDS0002 -compat')
//SYSPRINT DD     SYSOUT=H
//*******************************************************************
//**                                                               **
//**  note - use a + sign at the end of each line to indicate there**
//**         is another line to be processed.                      **
//**         use a ; at the end of each COMMAND                    **
//**                                                               **
//**         a single command can span multiple lines if each line **
//**         ends in a +.  when you have reached the end of the    **
//**         command, terminate the command with a ;               **
//**                                                               **
//*******************************************************************
//PAX1     EXEC PGM=IKJEFT01,REGION=0M
//SYSTSPRT DD  SYSOUT=*
//SYSEXEC  DD  DSN=SYS1.SBPXEXEC,DISP=SHR
//SYSTSIN  DD  *
 OSHELL /usr/sbin/mount -t ZFS -f PLEX.OLD.AGGR002.LDS0002           +
  /service2                                                        ; +
   /usr/sbin/mount -t ZFS -f PLEX.NEW.AGGR002.LDS0002 /service3    ; +
   cd /service2                                                    ; +
   pax -rwvCMX -p eW . /service3                                   ;
//* The result of these next two steps should show that
//* the new file system is smaller
//AGGRINF1 EXEC PGM=IOEZADM,REGION=0M,
// PARM=('aggrinfo PLEX.OLD.AGGR002.LDS0002 -long')
//SYSPRINT DD  SYSOUT=*
//STDOUT   DD  SYSOUT=*
//STDERR   DD  SYSOUT=*
//SYSUDUMP DD  SYSOUT=*
//CEEDUMP  DD  SYSOUT=*
/*
//AGGRINF2 EXEC PGM=IOEZADM,REGION=0M,
// PARM=('aggrinfo PLEX.NEW.AGGR002.LDS0002 -long')
//SYSPRINT DD  SYSOUT=*
//STDOUT   DD  SYSOUT=*
//STDERR   DD  SYSOUT=*
//SYSUDUMP DD  SYSOUT=*
//CEEDUMP  DD  SYSOUT=*
/*

This approach uses the pax command to copy the individual files and directories into an already formatted and empty zFS file system. Both file systems must be mounted. pax uses the z/OS® UNIX file and directory APIs to read and write each individual file and directory of the hierarchy of the file system. (It does not copy lower mounted file systems because of the -X and -M options.)

After you successfully copy the data, when you are comfortable with the new, smaller aggregate, you can delete the old aggregate.