Cache and Pool Entries in the Configuration File

Each configured data cache on the server has a block of information in the configuration file.

[Named Cache:cache_name]
     cache size = {size | DEFAULT}
     cache status = {mixed cache | log only | default data cache}
     cache replacement policy = {DEFAULT | 
          relaxed LRU replacement| strict LRU replacement }

Size units can be specified with:

P – pages (SAP ASE pages)
K – kilobytes (default)
M – megabytes
G – gigabytes

This example shows the configuration file entry for the default data cache:

[Named Cache:default data cache]
      cache size = DEFAULT
      cache status = default data cache
      cache replacement policy = strict LRU replacement

The default data cache entry is the only cache entry that is required for SAP ASE to start. It must include the cache size and cache status, and the status must be “default data cache.”

If the cache has pools configured, the pool, the block in the preceding example is followed by a block of information for each pool:

[16K I/O Buffer Pool]
        pool size = size
        wash size = size
        local async prefetch limit = DEFAULT

Note: In some cases, there is no configuration file entry for the pool in a cache. If you change the asynchronous prefetch percentage with sp_poolconfig, the change is written only to system tables, and not to the configuration file.

This example shows output from sp_cacheconfig, followed by the configuration file entries that match this cache and pool configuration:

Cache Name               Status    Type     Config Value Run Value
------------------------ --------- -------- ------------ ------------
default data cache       Active    Default      29.28 Mb     25.00 Mb
pubs_cache               Active    Mixed        20.00 Mb     20.00 Mb
pubs_log                 Active    Log Only      6.00 Mb     6.00 Mb
tempdb_cache             Active    Mixed         4.00 Mb     4.00 Mb
                                            ------------ ------------
                                     Total      59.28 Mb     55.00 Mb
=======================================================================
Cache: default data cache,   Status: Active,   Type: Default
     Config Size: 29.28 Mb,   Run Size: 29.28 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   3844 Kb      6.50 Mb     25.28 Mb     10
    4 Kb    512 Kb      4.00 Mb      4.00 Mb     10
=======================================================================
Cache: pubs_cache,   Status: Active,   Type: Mixed
     Config Size: 20.00 Mb,   Run Size: 20.00 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   2662 Kb      0.00 Mb     13.00 Mb     10
   16 Kb   1424 Kb      7.00 Mb      7.00 Mb     10
=======================================================================
Cache: pubs_log,   Status: Active,   Type: Log Only
     Config Size: 6.00 Mb,   Run Size: 6.00 Mb
     Config Replacement: relaxed LRU,   Run Replacement: relaxed LRU
     Config Partition:            1,   Run Partition:            1

IO Size  Wash Size Config Size  Run Size     APF Percent
-------- --------- ------------ ------------ -----------
    2 Kb    716 Kb      0.00 Mb      1.00 Mb     10
    4 Kb   1024 Kb      5.00 Mb      5.00 Mb     10
=======================================================================
Cache: tempdb_cache,   Status: Active,   Type: Mixed
     Config Size: 4.00 Mb,   Run Size: 4.00 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    818 Kb      0.00 Mb      4.00 Mb     10

This is the matching configuration file information:

[Named Cache:default data cache]
         cache size = 29.28M
         cache status = default data cache
        cache replacement policy = DEFAULT
        local cache partition number = DEFAULT

[2K I/O Buffer Pool]
        pool size = 6656.0000k
        wash size = 3844 K
        local async prefetch limit = DEFAULT

[4K I/O Buffer Pool]
        pool size = 4.0000M
        wash size = DEFAULT
        local async prefetch limit = DEFAULT

[Named Cache:pubs_cache]
        cache size = 20M
        cache status = mixed cache
        cache replacement policy = strict LRU replacement
        local cache partition number = DEFAULT

[16K I/O Buffer Pool]
        pool size = 7.0000M
        wash size = DEFAULT
        local async prefetch limit = DEFAULT

[Named Cache:pubs_log]
        cache size = 6M
        cache status = log only
        cache replacement policy = relaxed LRU replacement
        local cache partition number = DEFAULT

[4K I/O Buffer Pool]
        pool size = 5.0000M
        wash size = DEFAULT
        local async prefetch limit = DEFAULT
[Named Cache:tempdb_cache]
        cache size = 4M
        cache status = mixed cache
        cache replacement policy = DEFAULT
        local cache partition number = DEFAULT

Warning! Check the max memory configuration parameter and allow enough memory for other SAP ASE needs. If you assign too much memory to data caches in your configuration file, SAP ASE does not start. If this occurs, edit the configuration file to reduce the amount of space in the data caches, or increase the max memory allocated to SAP ASE.

See System Administration Guide: Volume 1 > Setting Configuration Parameters.