Viewing Information About Data Caches

Use sp_cacheconfig to create and configure named data caches. When you first install SAP ASE, it has a single cache named default data cache.

To see information about caches, enter:
SAP ASE displays results similar to:
Cache Name                Status    Type     Config Value  Run Value
------------------------- --------- -------- ------------ ------------
default data cache        Active    Default        0.00 Mb    59.44 Mb
                                             ------------ ------------
                                    Total          0.00 Mb    59.44 Mb
Cache: default data cache,   Status: Active,   Type: Default
     Config Size: 0.00 Mb,   Run Size: 59.44 Mb
     Config Replacement: strict LRU,   Run Replacement: strict LRU
     Config Partition:            1,   Run Partition:            1

IO Size  Wash Size Config Size  Run Size     APF Percent
-------- --------- ------------ ------------ -----------
    2 Kb   12174 Kb     0.00 Mb     59.44 Mb      10

Summary information for each cache is printed in a block at the top of the report, ending with a total size for all configured caches. For each cache, there is a block of information reporting the configuration for the memory pools in the cache.

The columns are:
  • Cache Name – gives the name of the cache.

  • Status – indicates whether the cache is active. Possible values are:

    • “Pend/Act” – the cache was just created but not yet active.

    • “Active” – the cache is currently active.

    • “Pend/Del” – the cache is being deleted. The cache size was reset to 0 using sp_cacheconfig and sp_poolconfig.

  • Type – indicates whether the cache can store data and log pages (“Mixed”) or log pages only (“Log Only”). Only the default cache has the type “Default.” You cannot change the type of the default data cache or change the type of any other cache to “Default.”

  • Config Value – displays the currently configured value. In the example output, the default data cache has not been explicitly configured, so its size is 0.

  • Run Value – displays the size that SAP ASE is currently using.

The second block of output begins with three lines of information that describe the cache. The first two lines repeat information from the summary block at the top. The third line, “Config Replacement” and “Run Replacement” shows the cache policy, which is either “strict LRU” or “relaxed LRU.” Run Replacement describes the setting in effect (either “strict LRU” or “relaxed LRU”). If the policy was changed since the server was restarted, the Config Replacement setting is different from the Run Replacement setting.

sp_cacheconfig then provides a row of information for each pool in the cache:

  • IO Size – shows the size of the buffers in the pool. The default size of the pool is the size of the server’s logical page. When you first configure a cache, all the space is assigned to the pool. Valid sizes are 2K, 4K, 8K, and 16K.

  • Wash Size – indicates the wash size for the pool.

  • Config Size and Run Size – display the configured size and the size currently in use. These may differ for other pools if you have tried to move space between them, and some of the space could not be freed.

  • Config Partition and Run Partition – display the configured number of cache partitions and the number of partitions currently in use. These may differ if you have changed the number of partitions since last restart.

  • APF Percent – displays the percentage of the pool that can hold unused buffers brought in by asynchronous prefetch.

A summary line prints the total size of the cache or caches displayed.

Related concepts
Changing the Wash Area for a Memory Pool
Related tasks
Configuring Data Caches