What is contained in the Subsystem Analyzer FMT_WIO column?

Document ID : KB000050567
Last Modified Date : 14/02/2018
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Introduction: 

This article describes what is contained in the Subsystem Analyzer FMT_WIO column.

Question: 

What is contained in the Subsystem Analyzer FMT_WIO column?

Environment:  

z/OS 1.11 and above.

Answer: 

This column contains a count of the DB2 pre-formatting I/O's of new pages in a table space during execution time.

A common reason would be Inserts which cause new extents to be built and new pages to be formatted by DB2. 

Additional Information:

If the PREFORMAT option is used in a LOAD or REORG utility, depending upon the size of the object, this could generate a substantial amount of "Format Write I/O's".