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Description of QMDC

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From Kris Buelens, IBM Belgium

QMDC collects IO and MDC counts on minidisk basis from the VDEVBLOK. These counters are incremented until the Mdisk is DETACHed.

But, QMDC can compare the counts between two runs, so giving you an idea about the MDC hit% in a shorter period.

Changes:

7 Aug 1998: Avoid problems when a TDISK appears in col1 of Q SYSTEM ALL

1 Sep 1998: Avoid REXX abend on machines with >953 Meg real storage

Warning:

On VM/ESA V2.2.0 we detected that the IO counters maintained in the VDEV block are not always correctly updated. This means that QMDC cannot give correct results. Probably all VM/ESA releases with "enhanced MDC" (V1.2.2 till V2.3.0) are affected as well. The VM lab is aware of the problem and looking for a fix, either in a PTF or in a later release.