RCVOPT parameter: Difference between revisions

From m204wiki
Jump to navigation Jump to search
m (misc cleanup)
m (misc formatting)
 
(7 intermediate revisions by 2 users not shown)
Line 11: Line 11:
<dd>All
<dd>All
<dt>Introduced
<dt>Introduced
<dd><var class="product">Model 204 V6.1</var> or earlier
<dd><var class="product">Model 204 V2.1</var> or earlier
</dl>
</dl>


Line 22: Line 22:


<tr><th><var>X'01'</var></th>
<tr><th><var>X'01'</var></th>
<td>Checkpoints are taken.</td></tr>
<td>[[Checkpoints: Storing before-images of changed pages|Checkpoints]] are taken.</td></tr>


<tr><th><var>X'08'</var></th>
<tr><th><var>X'08'</var></th>
<td>Roll forward information is logged into the journal stream.</td></tr>
<td>[[RESTART command#Rolling back and rolling forward|Roll forward]] information is logged into the journal stream.</td></tr>


<tr><th><var>X'20'</var></th>
<tr><th><var>X'20'</var></th>
<td>Do not flush the dirty pages in a file that does not do pre-imaging (<var>[[FRCVOPT parameter|FRCVOPT]]</var> X'20' set) during a subtransaction checkpoint. This bit only has an effect in Model 204 7.6 and later.  
<td>Do not flush the dirty pages in a file that does not do pre-imaging (<var>[[FRCVOPT parameter|FRCVOPT]]</var> X'20' set) during a [[Checkpoints: Storing before-images of changed pages#Overview of sub-transaction checkpoints|subtransaction checkpoint]]. This bit has an effect in Model&nbsp;204 7.6 and later; for V7.5, it requires an appropriate maintenance zap.  
<p>
<p>
One use of this setting is to set <var>FRCVOPT</var> X'20' for a file that holds <var class="product">[[SirFact]]</var> dumps, which can get quite large. This will prevent a large <var class="product">SirFact</var> dump from causing a subtransaction checkpoint to take a very long time. While this might result in a <var class="product">SirFact</var> dump being lost if the system crashes, such a loss is probably not that critical, so its risk is probably well worth the benefit of faster subtransaction checkpoints.</p></td></tr>
One use of this setting is to set <var>FRCVOPT</var> X'20' for a file that holds <var class="product">[[SirFact]]</var> dumps, which can get quite large. This bit prevents a large <var class="product">SirFact</var> dump from causing a subtransaction checkpoint to take a very long time. While this might result in a <var class="product">SirFact</var> dump being lost if the system crashes, such a loss is probably not that critical, so its risk is probably well worth the benefit of faster subtransaction checkpoints.</p></td></tr>
</table>
</table>


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

Latest revision as of 16:20, 22 May 2017

Recovery options

Summary

Default value
0
Parameter type
System
Where set
On User 0's parameter line
Related products
All
Introduced
Model 204 V2.1 or earlier

Description

Valid settings of RCVOPT are (options can be summed):

Setting Meaning
X'01' Checkpoints are taken.
X'08' Roll forward information is logged into the journal stream.
X'20' Do not flush the dirty pages in a file that does not do pre-imaging (FRCVOPT X'20' set) during a subtransaction checkpoint. This bit has an effect in Model 204 7.6 and later; for V7.5, it requires an appropriate maintenance zap.

One use of this setting is to set FRCVOPT X'20' for a file that holds SirFact dumps, which can get quite large. This bit prevents a large SirFact dump from causing a subtransaction checkpoint to take a very long time. While this might result in a SirFact dump being lost if the system crashes, such a loss is probably not that critical, so its risk is probably well worth the benefit of faster subtransaction checkpoints.