| Parameter | Specify . . . | Minimum | Maximum | Default |
|---|---|---|---|---|
| LRDP | the size (in bytes) of the cluster block update "redo" pool. | 0; or 80,000 | 2,147,483,647 | LFIOP value |
With deferred caching, the publication of updated blocks to the cache may fail due to conflicting updates to the same blocks by other nuclei in the cluster. Every cluster nucleus is therefore capable of redoing the updates it has not yet written to the cache. The nucleus maintains information about these updates in the "redo" pool.
Otherwise, with deferred caching enabled, the minimum pool size is 80,000 bytes and the (theoretical) maximum size is 2,147,483,647 bytes. If no value is specified, the nucleus takes as default for LRDP the value of the LFIOP parameter ).
Different nuclei in the same cluster can have different settings of LRDP. It is also possible, although not recommended, to run one nucleus with LRDP=0 and a peer nucleus with LRDP>0.
If the redo pool specification is too small and the pool runs full, the nucleus is forced to write updated blocks to the cache before the end of transaction. Such additional cache writes will impair system performance.
LRDP uses the value of the LFIOP parameter as its default. The LFIOP parameter enables asynchronous buffer flush operation and sets the I/O pool size.
The LRDP parameter is only effective in an Adabas cluster nucleus; that is, CLUSTER={SYSPLEX | LOCAL} and NUCID is nonzero.
The nucleus reports on the usage (high watermark) of the redo pool in a shutdown statistic and in the response to the DRES command from the operator console or from ADADBS OPERCOM.
