LDKBMWND parameter: Difference between revisions
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==Description== | ==Description== | ||
<p>An anticipatory write window that starts writes for any modified buffers that enter the window</p> | <p> | ||
<p>When an anticipatory write for a modified buffer completes, the buffer is immediately reusable. </p> | An anticipatory write window that starts writes for any modified buffers that enter the window</p> | ||
<p>If <var>[[ | <p> | ||
<p>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).</p> | When an anticipatory write for a modified buffer completes, the buffer is immediately reusable. </p> | ||
<p>Refer to the | <p> | ||
If <var>[[NLRUQ parameter|NLRUQ]]</var> is set greater than 1, then the value of <var>LDKBMWND</var> is rounded up to a multiple of <var>NLRUQ</var>. <var>LDKBMWND</var> has a minimum size of one (1). </p> | |||
<p> | |||
High values of <var>LDKBMWND</var> 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).</p> | |||
<p> | |||
Refer to [[Performance monitoring and tuning#Disk buffer monitor statistics and parameters|Disk buffer monitor statistics and parameters]] and [[Defining the runtime environment (CCAIN)#Disk buffers and Model 204 storage|Disk buffers and Model 204 storage]] for more information about disk buffers. </p> | |||
[[Category:System parameters]] | [[Category:System parameters]] | ||
[[Category:Parameters]] | [[Category:Parameters]] | ||
Revision as of 16:48, 5 November 2015
# 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 Disk buffer monitor statistics and parameters and Disk buffers and Model 204 storage for more information about disk buffers.