LDKBMWND parameter: Difference between revisions
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<dl> | <dl> | ||
<dt>Default value | <dt>Default value | ||
<dd><var>[[NSERVS_parameter|NSERVS]]</var> plus 1 for releases up to and including V7.4. From v7.5 onwards, the default has been changed to ( 0.5 * NUMBUF ) | <dd><var>[[NSERVS_parameter|NSERVS]]</var> plus 1 for releases up to and including V7.4. From v7.5 onwards, the default has been changed to ( 0.5 * <var>[[NUMBUF_parameter|NUMBUF]]</var> ) | ||
<dt>Parameter type | <dt>Parameter type | ||
<dd>System | <dd>System | ||
Revision as of 10:25, 27 November 2014
# of pages in DKBM-BTB anticipatory write window
Summary
- Default value
- NSERVS plus 1 for releases up to and including V7.4. From v7.5 onwards, the default has been changed to ( 0.5 * NUMBUF )
- Parameter type
- System
- Where set
- On User 0's parameter line by system manager
- Related products
- All
- Introduced
- Model 204 V6.1 or earlier
Description
An anticipatory write window that starts writes for any modified buffers that enter the window
When an anticipatory write for a modified buffer completes, the buffer is immediately reusable.
If NLRUQ is set greater than 1, then the value of LDKBMWND is rounded up to a multiple of NLRUQ. LDKBMWND has a minimum size of one (1).
High values of LDKBMWND might unnecessarily increase the number of writes done (measured by the DKWR statistic). Low values might cause excessive waiting for buffers (measured by the DKSWAIT statistic).
Refer to the Model 204 System Manager's Guide for more information about disk buffer monitor parameters and statistics.