Exclusive buffer waits

Products

• IDMS

Issue/Introduction

Non-zero values are being shown for exclusive buffer waits on Performance Monitor's online screens and batch reports (PMIRPT21, PMIRPT22 and PMIRPT23).

Environment

Release: All supported releases.

Resolution

These are an indication of contention by multiple transactions for update access to the same database page.

There is a good technical description of the various types of buffer waits at 89-08-1171 WHAT DOES A 'BUFFER WAIT' MEAN?. This is an old document but it describes internal technical information which is still correct.

The most common things to look for are:

• Database pages more than 70% full in the areas/files that use the buffer - the pages in question are most likely Space Management Pages.

• Concurrent access to "OOAK" (one-of-a-kind) style database record definitions.

Note that this is generally not something that can be addressed by simply adding pages to the buffer.