LDKBMWND parameter - Revision history

JAL: add link

2016-09-22T21:18:03Z

add link

← Older revision		Revision as of 21:18, 22 September 2016
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	<p class="code">NLRUQ * ((NSERVS + NSUBTKS) * MAXOBUF + 15)</p>		<p class="code">NLRUQ * ((NSERVS + NSUBTKS) * MAXOBUF + 15)</p>
	<p>		<p>
	If the current value of <var>NUMBUF</var> exceeds this value and is a multiple of <var>NLRUQ</var>, no further adjustments to <var>NUMBUF</var> are made.		If the current value of <var>NUMBUF</var> exceeds this value and is a multiple of <var>[[NLRUQ parameter\|NLRUQ]]</var>, no further adjustments to <var>NUMBUF</var> are made.
	</p>		</p>
	Following that, if a value for <var>LDKBMWND</var> is specified in CCAIN and is greater than <code>0.5*NUMBUF</code>, the value can still be adjusted:		Following that, if a value for <var>LDKBMWND</var> is specified in CCAIN and is greater than <code>0.5*NUMBUF</code>, the value can still be adjusted:

JAL: add 7.7 change

2016-08-25T17:44:03Z

add 7.7 change

← Older revision		Revision as of 17:44, 25 August 2016
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	<dl>		<dl>
	<dt>Default value		<dt>Default value
	<dd>~~(version 7~~.4 and earlier) <var>[[NSERVS_parameter\|NSERVS]]</var> plus 1.		<dd>V7.4 and earlier: <var>[[NSERVS_parameter\|NSERVS]]</var> plus 1
	<p>~~(version 7~~.5 and later) A minimum of ( 0.5 * <var>[[NUMBUF_parameter\|NUMBUF]]</var> ).</p>		<p>
	Before the value of LDKBMWND is adjusted or recalculated, the minimum size of NUMBUF must first be determined by this formula:		V7.5 and later: A minimum of ( 0.5 * <var>[[NUMBUF_parameter\|NUMBUF]]</var> )</p>
			<p>
			V7.7 and later: If <var>[[NUMBUFG parameter\|NUMBUFG]]</var> is greater than 0, <var>LDKBMWND</var> is ignored </p>

			Before the value of <var>LDKBMWND</var> is adjusted or recalculated, the minimum size of <var>NUMBUF</var> must first be determined by this formula:
	<p class="code">NLRUQ * ((NSERVS + NSUBTKS) * MAXOBUF + 15)</p>		<p class="code">NLRUQ * ((NSERVS + NSUBTKS) * MAXOBUF + 15)</p>
	<p>If the current value of NUMBUF exceeds this value and ~~the value~~ is a multiple of NLRUQ, no further adjustments to NUMBUF are made.</p>		<p>
	Following that, if a value for LDKBMWND is specified in CCAIN and ~~that value~~ is greater than 0.5*NUMBUF, the value can still be adjusted:		If the current value of <var>NUMBUF</var> exceeds this value and is a multiple of <var>NLRUQ</var>, no further adjustments to <var>NUMBUF</var> are made.
			</p>
			Following that, if a value for <var>LDKBMWND</var> is specified in CCAIN and is greater than <code>0.5*NUMBUF</code>, the value can still be adjusted:
	<ul>		<ul>
	<li>The final value must be an even multiple of NLRUQ</li>		<li>The final value must be an even multiple of <var>NLRUQ</var></li>
	<li>The final value must not be greater than NUMBUF minus the total number of buffers that might possibly be open at any one time:		<li>The final value must <i>not</i> be greater than <var>NUMBUF</var> minus the total number of buffers that might possibly be open at any one time:
	<p class="code">NUMBUF - (((NSERVS+NSUBTKS)MAXOBUF)+14)NLRUQ</p> </li>		<p class="code">NUMBUF - (((NSERVS+NSUBTKS)MAXOBUF)+14)NLRUQ</p> </li>
	</ul>		</ul>
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	==Description==		==Description==
	<p>		<p>
	An anticipatory write window that starts writes for any modified buffers that enter the window.</p>		<var>LDKBMWND</var> specifies an anticipatory write window that starts writes for any modified below-the-bar buffers that enter the window.</p>
	<p>		<p>
	When an anticipatory write for a modified buffer completes, the buffer is immediately reusable. </p>		When an anticipatory write for a modified buffer completes, the buffer is immediately reusable. </p>
	<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>		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 anticipatory write windows and disk buffers. </p>		==See also==
			<ul>
			<li>[[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 anticipatory write windows and disk buffers </li>

			<li><var>[[LDKBMWNG parameter\|LDKBMWNG]]</var> </li>
			</ul>

	[[Category:System parameters]]		[[Category:System parameters]]
	[[Category:Parameters]]		[[Category:Parameters]]

JDamon: Further clarification of the relationship between NUMBUF and LDKBMWND

2016-05-06T17:10:41Z

Further clarification of the relationship between NUMBUF and LDKBMWND

← Older revision		Revision as of 17:10, 6 May 2016
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	<dd>(version 7.4 and earlier) <var>[[NSERVS_parameter\|NSERVS]]</var> plus 1.		<dd>(version 7.4 and earlier) <var>[[NSERVS_parameter\|NSERVS]]</var> plus 1.
	<p>(version 7.5 and later) A minimum of ( 0.5 * <var>[[NUMBUF_parameter\|NUMBUF]]</var> ).</p>		<p>(version 7.5 and later) A minimum of ( 0.5 * <var>[[NUMBUF_parameter\|NUMBUF]]</var> ).</p>
	~~The~~ minimum size of ~~MINBUF, MAXBUF, and~~ NUMBUF is determined by this formula:		Before the value of LDKBMWND is adjusted or recalculated, the minimum size of NUMBUF must first be determined by this formula:
	<p class="code">NLRUQ * ((NSERVS + NSUBTKS) * MAXOBUF + 15)</p>		<p class="code">NLRUQ * ((NSERVS + NSUBTKS) * MAXOBUF + 15)</p>
	<p>If the current ~~setting~~ of NUMBUF exceeds this value and the value is a multiple of NLRUQ, no further adjustments are made.</p>		<p>If the current value of NUMBUF exceeds this value and the value is a multiple of NLRUQ, no further adjustments to NUMBUF are made.</p>
	Following that, if a value for LDKBMWND is specified in CCAIN and that value is greater than 0.5*NUMBUF, the value can still be adjusted:		Following that, if a value for LDKBMWND is specified in CCAIN and that value is greater than 0.5*NUMBUF, the value can still be adjusted:
	<ul>		<ul>

ELowell: /* Summary */

2016-04-28T20:47:52Z

Summary

← Older revision		Revision as of 20:47, 28 April 2016
Line 5:		Line 5:
	<dd>(version 7.4 and earlier) <var>[[NSERVS_parameter\|NSERVS]]</var> plus 1.		<dd>(version 7.4 and earlier) <var>[[NSERVS_parameter\|NSERVS]]</var> plus 1.
	<p>(version 7.5 and later) A minimum of ( 0.5 * <var>[[NUMBUF_parameter\|NUMBUF]]</var> ).</p>		<p>(version 7.5 and later) A minimum of ( 0.5 * <var>[[NUMBUF_parameter\|NUMBUF]]</var> ).</p>
	MINBUF, MAXBUF, and~~/or~~ NUMBUF ~~will first be adjusted according to~~ this formula:		The minimum size of MINBUF, MAXBUF, and NUMBUF is determined by this formula:
	<p class="code">NLRUQ * ((NSERVS + NSUBTKS) * MAXOBUF + 15)</p>		<p class="code">NLRUQ * ((NSERVS + NSUBTKS) * MAXOBUF + 15)</p>
			<p>If the current setting of NUMBUF exceeds this value and the value is a multiple of NLRUQ, no further adjustments are made.</p>
	Following that, if a value for LDKBMWND is specified in CCAIN and that value is greater than 0.5*NUMBUF, the value can still be adjusted:		Following that, if a value for LDKBMWND is specified in CCAIN and that value is greater than 0.5*NUMBUF, the value can still be adjusted:
	<ul>		<ul>

ELowell: /* Description */

2016-04-28T20:15:29Z

Description

← Older revision		Revision as of 20:15, 28 April 2016
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	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>		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>		<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>		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 anticipatory write windows and disk buffers. </p>

	[[Category:System parameters]]		[[Category:System parameters]]
	[[Category:Parameters]]		[[Category:Parameters]]

ELowell: /* Summary */

2016-04-28T20:00:17Z

Summary

← Older revision		Revision as of 20:00, 28 April 2016
Line 5:		Line 5:
	<dd>(version 7.4 and earlier) <var>[[NSERVS_parameter\|NSERVS]]</var> plus 1.		<dd>(version 7.4 and earlier) <var>[[NSERVS_parameter\|NSERVS]]</var> plus 1.
	<p>(version 7.5 and later) A minimum of ( 0.5 * <var>[[NUMBUF_parameter\|NUMBUF]]</var> ).</p>		<p>(version 7.5 and later) A minimum of ( 0.5 * <var>[[NUMBUF_parameter\|NUMBUF]]</var> ).</p>
	MINBUF, MAXBUF, and/or NUMBUF will first be adjusted according to this formula:~~<br />~~		MINBUF, MAXBUF, and/or NUMBUF will first be adjusted according to this formula:
	<code>NLRUQ * ((NSERVS + NSUBTKS) * MAXOBUF + 15)</~~code~~>		<p class="code">NLRUQ * ((NSERVS + NSUBTKS) * MAXOBUF + 15)</p>

	Following that, if a value for LDKBMWND is specified in CCAIN and that value is greater than 0.5*NUMBUF, the value can still be adjusted:		Following that, if a value for LDKBMWND is specified in CCAIN and that value is greater than 0.5*NUMBUF, the value can still be adjusted:
	<ul>		<ul>
	<li>The final value must be an even multiple of NLRUQ</li>		<li>The final value must be an even multiple of NLRUQ</li>
	<li>The final value must not be greater than NUMBUF minus the total number of buffers that might possibly be open at any one time: ~~<br />~~		<li>The final value must not be greater than NUMBUF minus the total number of buffers that might possibly be open at any one time:
	<code>NUMBUF - (((NSERVS+NSUBTKS)MAXOBUF)+14)NLRUQ</~~code~~> </li>		<p class="code">NUMBUF - (((NSERVS+NSUBTKS)MAXOBUF)+14)NLRUQ</p> </li>
	</ul>		</ul>
	<dt>Parameter type		<dt>Parameter type

ELowell: /* Summary */

2016-04-28T19:31:38Z

Summary

← Older revision		Revision as of 19:31, 28 April 2016
Line 3:		Line 3:
	<dl>		<dl>
	<dt>Default value		<dt>Default value
	<dd><var>[[NSERVS_parameter\|NSERVS]]</var> plus 1 ~~-- for version 7.4 and earlier~~.		<dd>(version 7.4 and earlier) <var>[[NSERVS_parameter\|NSERVS]]</var> plus 1.
	<p>A minimum of ( 0.5 * <var>[[NUMBUF_parameter\|NUMBUF]]</var> ) ~~-- for version 7.5 and later~~.</p>		<p>(version 7.5 and later) A minimum of ( 0.5 * <var>[[NUMBUF_parameter\|NUMBUF]]</var> ).</p>
	NUMBUF will first be adjusted ~~(rounded up)~~ to ~~be an even multiple of~~ <~~var~~>[[NLRUQ ~~parameter\|NLRUQ]]~~</~~var~~>. Following that, if a value for LDKBMWND is specified in CCAIN and that value is greater than .5*NUMBUF, the value can still be adjusted:		MINBUF, MAXBUF, and/or NUMBUF will first be adjusted according to this formula:<br />
			<code>NLRUQ * ((NSERVS + NSUBTKS) * MAXOBUF + 15)</code>

			Following that, if a value for LDKBMWND is specified in CCAIN and that value is greater than 0.5*NUMBUF, the value can still be adjusted:
	<ul>		<ul>
	<li>The final value must be an even multiple of NLRUQ</li>		<li>The final value must be an even multiple of NLRUQ</li>
	<li>The final value must not be greater than NUMBUF minus the total number of buffers that might possibly be open at any one time: ~~that is,~~ <br />NUMBUF - (((NSERVS+NSUBTKS)MAXOBUF)+14)NLRUQ </li>		<li>The final value must not be greater than NUMBUF minus the total number of buffers that might possibly be open at any one time: <br />
			<code>NUMBUF - (((NSERVS+NSUBTKS)MAXOBUF)+14)NLRUQ</code> </li>
	</ul>		</ul>
	<dt>Parameter type		<dt>Parameter type

ELowell: /* Description */

2016-04-28T19:19:46Z

Description

← Older revision		Revision as of 19:19, 28 April 2016
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	<p>		<p>
	When an anticipatory write for a modified buffer completes, the buffer is immediately reusable. </p>		When an anticipatory write for a modified buffer completes, the buffer is immediately reusable. </p>
	~~<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>		<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>		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>

ELowell at 16:30, 28 April 2016

2016-04-28T16:30:48Z

← Older revision		Revision as of 16:30, 28 April 2016
Line 3:		Line 3:
	<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 a~~ minimum of ( 0.5 * <var>[[NUMBUF_parameter\|NUMBUF]]</var> ). NUMBUF will first be adjusted (rounded up) to be an even multiple of NLRUQ. Following that, if a value for LDKBMWND is specified in CCAIN and that value is greater than .5*NUMBUF, the value ~~may~~ still be adjusted:		<dd><var>[[NSERVS_parameter\|NSERVS]]</var> plus 1 -- for version 7.4 and earlier.
			<p>A minimum of ( 0.5 * <var>[[NUMBUF_parameter\|NUMBUF]]</var> ) -- for version 7.5 and later.</p>
			NUMBUF will first be adjusted (rounded up) to be an even multiple of <var>[[NLRUQ parameter\|NLRUQ]]</var>. Following that, if a value for LDKBMWND is specified in CCAIN and that value is greater than .5*NUMBUF, the value can still be adjusted:
			<ul>
	<li>The final value must be an even multiple of NLRUQ</li>		<li>The final value must be an even multiple of NLRUQ</li>
	<li>The final value must not be greater than NUMBUF minus the total number of buffers that might possibly be open at any one time: ~~i.e~~ NUMBUF - (((NSERVS+NSUBTKS)MAXOBUF)+14)NLRUQ </li>		<li>The final value must not be greater than NUMBUF minus the total number of buffers that might possibly be open at any one time: that is, <br />NUMBUF - (((NSERVS+NSUBTKS)MAXOBUF)+14)NLRUQ </li>
			</ul>
	<dt>Parameter type		<dt>Parameter type
	<dd>System		<dd>System
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	==Description==		==Description==
	<p>		<p>
	An anticipatory write window that starts writes for any modified buffers that enter the window</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>		When an anticipatory write for a modified buffer completes, the buffer is immediately reusable. </p>

JDamon: Added a detailed description on how LDKBMWND is calculated

2016-04-27T16:44:51Z

Added a detailed description on how LDKBMWND is calculated

← Older revision		Revision as of 16:44, 27 April 2016
Line 3:		Line 3:
	<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 * <var>[[NUMBUF_parameter\|NUMBUF]]</var> )		<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 a minimum of ( 0.5 * <var>[[NUMBUF_parameter\|NUMBUF]]</var> ). NUMBUF will first be adjusted (rounded up) to be an even multiple of NLRUQ. Following that, if a value for LDKBMWND is specified in CCAIN and that value is greater than .5*NUMBUF, the value may still be adjusted:
			<li>The final value must be an even multiple of NLRUQ</li>
			<li>The final value must not be greater than NUMBUF minus the total number of buffers that might possibly be open at any one time: i.e NUMBUF - (((NSERVS+NSUBTKS)MAXOBUF)+14)NLRUQ </li>
	<dt>Parameter type		<dt>Parameter type
	<dd>System		<dd>System