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VSAM Assist - use Merge instead of DUMP
VSAM Assist users,
You can save a bunch of time on routine backups by using the VSAM Assist MERGE utility. It's a variation of the DUMP command that backs up data sets from DASD only if they've been updated since the last backup.
How does this help? The data sets being backed up are checked for last update. If they're not updated since the backup specified in the MERGEDD, VSAM Assist skips the 'DUMP', for that data set since it already has a current backup and copies the data set from the old backup to the new backup.
Once VSAM Assist determines the data set is unchanged, the job is 'done' with that data set, it is freed and the version on the existing MERGEDD backup is copied to the new backup. This can be helpful in a number of ways, particularly for very large VSAM data sets, ones that have to be backed up regularly but aren't necessarily updated frequently or when backing up a group of data sets. The copy function generally performs better than the dump and for situations where you need to wring every last bit of performance out, this should help.
Merge lends itself well to using Generation Data Groups (GDGs) for the MERGEDD and TODD data sets, but that's not a requirement. One customer has used a REXX to setup this JCL & command to vary the data sets by julian date
We have a knowledgebase entry covering this:
http://csgateway.emc.com/primus.asp?id=emc87288
Details are covered in the VSAM Assist User Guide:
http://powerlink.emc.com/km/live1/en_US/Offering_Technical/Technical_Documentation/300-001-779.pdf#page=183
Example:
...
//VABKUP1 EXEC PGM=VSAMASST
//BKUP DD DSN= myvsam.bkup(+1),
// DISP=(,CATLG,DELETE),
// UNIT=SYSDA,SPACE=(CYL,(50,5),RLSE)
//MERGE DD DSN= myvsam.bkup(0),
// DISP=SHR
//SYSIN DD *
DUMP TODD=BKUP,
MERDD=MERGE,
INCGEN=myvsam.**
/*
//
The above example will Dump all the data sets under the 'myvsam' high level qualifier that have been updated since the backup myvsam.bkup(0) was created.
The remaining data sets on the backup myvsam.bkup(0) are copied to the "+1" or new generation data set.
Dave Yates
EMC TSE3
Benevolent Host S/W & Mainframe Forum Moderator
You can save a bunch of time on routine backups by using the VSAM Assist MERGE utility. It's a variation of the DUMP command that backs up data sets from DASD only if they've been updated since the last backup.
How does this help? The data sets being backed up are checked for last update. If they're not updated since the backup specified in the MERGEDD, VSAM Assist skips the 'DUMP', for that data set since it already has a current backup and copies the data set from the old backup to the new backup.
Once VSAM Assist determines the data set is unchanged, the job is 'done' with that data set, it is freed and the version on the existing MERGEDD backup is copied to the new backup. This can be helpful in a number of ways, particularly for very large VSAM data sets, ones that have to be backed up regularly but aren't necessarily updated frequently or when backing up a group of data sets. The copy function generally performs better than the dump and for situations where you need to wring every last bit of performance out, this should help.
Merge lends itself well to using Generation Data Groups (GDGs) for the MERGEDD and TODD data sets, but that's not a requirement. One customer has used a REXX to setup this JCL & command to vary the data sets by julian date
We have a knowledgebase entry covering this:
http://csgateway.emc.com/primus.asp?id=emc87288
Details are covered in the VSAM Assist User Guide:
http://powerlink.emc.com/km/live1/en_US/Offering_Technical/Technical_Documentation/300-001-779.pdf#page=183
Example:
...
//VABKUP1 EXEC PGM=VSAMASST
//BKUP DD DSN= myvsam.bkup(+1),
// DISP=(,CATLG,DELETE),
// UNIT=SYSDA,SPACE=(CYL,(50,5),RLSE)
//MERGE DD DSN= myvsam.bkup(0),
// DISP=SHR
//SYSIN DD *
DUMP TODD=BKUP,
MERDD=MERGE,
INCGEN=myvsam.**
/*
//
The above example will Dump all the data sets under the 'myvsam' high level qualifier that have been updated since the backup myvsam.bkup(0) was created.
The remaining data sets on the backup myvsam.bkup(0) are copied to the "+1" or new generation data set.
Dave Yates
EMC TSE3
Benevolent Host S/W & Mainframe Forum Moderator