Setting a Named Cache for dbcc

If you use a named cache for dbcc checkstorage, you might need to adjust the SAP ASE configuration parameters.

During a dbcc checkstorage operation, the workspaces are temporarily bound to a cache which also reads the target database. Using a named cache that is dedicated to dbcc minimizes the impact of the database check on other users and improves performance. You can create a separate cache for each dbcc checkstorage operation that runs concurrently, or you can create one cache that is large enough to fit the total requirements of the concurrent operations. The size required for optimum performance depends on the size of the target database and distributions of data in that database. dbcc checkstorage requires a minimum of 640K of buffers (each buffer is one extent) per worker process in the named cache.

For best performance, assign most of the dedicated cache to the buffer pool and do not partition the cache. The recommended cache size is the minimum size for the buffer pool. Add the size of the one-page pool to this value.

If you dedicate a cache for dbcc checkstorage, the command does not require more than the minimum one-page buffer pool. If the cache is shared, you can improve the performance of dbcc checkstorage by increasing the buffer pool size before running the operation, and reducing the size after the operation is complete. The buffer pool requirements are the same for a shared cache. However, while a shared cache may meet the size requirement, other demands on the cache might limit the buffer availability to dbcc checkstorage and greatly impact the performance of both checkstorage and SAP ASE as a whole.

Note: Because SAP ASE may issue error messages 9946 or 9947 if you dedicate a cache partition for dbcc checkstorage, SAP recommends that you dedicate a named cache for dbcc checkstorage.

To configure SAP ASE with a named cache for dbcc checkstorage operations, use sp_cacheconfig and sp_poolconfig.