NUMBUFG parameter: Difference between revisions

From m204wiki
Jump to navigation Jump to search
m (add clarifying phrase)
m (→‎Description: add clarifying phrase)
Line 26: Line 26:
If <var>NUMBUFG</var> is specified, no buffer pool buffers are built BTB; all buffers are ATB. Model&nbsp;204 obtains exactly the <var>NUMBUFG</var> number of buffers. </p>
If <var>NUMBUFG</var> is specified, no buffer pool buffers are built BTB; all buffers are ATB. Model&nbsp;204 obtains exactly the <var>NUMBUFG</var> number of buffers. </p>
<p>
<p>
<var>NUMBUFG</var> essentially replaces both <var>MINBUF</var> and <var>MAXBUF</var>: <var>MINBUF</var> is automatically reset to 0, and <var>MAXBUF</var> and <var>SPCORE</var> are ignored. </p>
In this case, <var>NUMBUFG</var> essentially replaces the BTB parameters: <var>NUMBUF</var> and <var>MINBUF</var> are automatically reset to 0, and <var>MAXBUF</var> and <var>SPCORE</var> are ignored. </p>
</li>
</li>
</ul>
</ul>

Revision as of 18:32, 24 August 2016

Number of above-the-bar buffers

Summary

Default value
0
Parameter type
System
Where set
Not resettable
Related products
All
Introduced
Model 204 V7.1

Description

Allocate this number of buffer pool buffers above the bar (ATB).

  • Prior to version 7.7 of Model 204:

    NUMBUFG specifies the number of buffer pool buffers built ATB, while the number of buffer pool buffers built BTB is based on the setting of MINBUF, MAXBUF, and SPCORE.

  • As of version 7.7:

    If NUMBUFG is specified, no buffer pool buffers are built BTB; all buffers are ATB. Model 204 obtains exactly the NUMBUFG number of buffers.

    In this case, NUMBUFG essentially replaces the BTB parameters: NUMBUF and MINBUF are automatically reset to 0, and MAXBUF and SPCORE are ignored.

The maximum number of buffers is 2**31/3, or 715,827,882, which limits buffer pools to 4.2 terabytes or less.

The minimum number of ATB buffers is:

NLRUQG * ((NSERVS + NSUBTKS) * MAXOBUF + 15)

If you set NUMBUFG to a lower value, it is reset to the calculated value.

See also

For more information about setting NUMBUFG, see Managing ATB storage with NUMBUFG.