RCVOPT parameter: Difference between revisions
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<dd>All | <dd>All | ||
<dt>Introduced | <dt>Introduced | ||
<dd><var class="product">Model 204 | <dd><var class="product">Model 204 V2.1</var> or earlier | ||
</dl> | </dl> | ||
==Description== | ==Description== | ||
< | <p> | ||
Valid settings of <var>RCVOPT</var> are (options can be summed):</p> | |||
<table> | <table> | ||
<tr><th>Setting</th><th>Meaning</th></tr> | <tr class="head"><th>Setting</th> | ||
<tr><th | <th>Meaning</th></tr> | ||
<tr><th | |||
<tr><th | <tr><th><var>X'01'</var></th> | ||
<td>[[Checkpoints: Storing before-images of changed pages|Checkpoints]] are taken.</td></tr> | |||
<tr><th><var>X'08'</var></th> | |||
<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> | |||
<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 204 7.6 and later; for V7.5, it requires an appropriate maintenance zap. | |||
<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 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. |