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DFHSM as a Problem-solving Tool

DFHSM is commonly used to take incremental backups when a dataset has changed. If you can find out what he knows, this can help you answer that age-old question that always gets asked when something breaks: "What changed?". Since DFHSM normally takes a new incremental backup automatically only when something changes, by doing an HLIST dsn BCDS, you can get a picture of when the dataset was last changed.

Note that the rules about when incremental backups are taken will vary from installation to installation and your installation may even have different rules for different datasets.

By looking at the information in the format 1 DSCB, you can also find out if a dataset has been changed since the last backup was taken. It helps if you have a product like "StarTool" or the shareware PDS command.

You can get specific information about who and when by reviewing SMF type 15 records (for non-VSAM datasets).

DFHSM can also restore an older version of the dataset under a different name which will allow you to compare the two versions to see what changed.

Of course, this is no substitute for good change management but it can be useful if things somehow fall between the cracks.

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