Equation 1: Estimate Size of Database Cache

dbcachesize = SUM(allDB4files)

Note: Equation 1 gives you a very rough estimation for dbcachesize. When estimating database cache size, include only those database (db4) files that your operations need. For example, if your directory server only needs to support exact search requests on the “cn” attribute, you may need just 354MB dbcache instead of 685MB dbcache which is the sum of all database (db4) files for the 250K databases. For more information about how to manage indexes, see the HP-UX Directory Server administrator guide.

Figure 2 shows performance results using the Montvale-based test configuration (8 CPUs@1.6GHz) measured against different values of the nsslapd-dbcachesize parameter.

Figure 2: Performance based on nsslapd-dbcachesize

operations/sec

20000

 

 

 

 

 

18000

 

 

 

 

 

16000

 

 

 

 

 

14000

 

 

 

 

 

12000

 

 

 

 

 

10000

 

 

 

 

 

8000

 

 

 

 

250k, 2 dual-core CPUs

6000

 

 

 

 

 

4000

 

 

 

 

 

2000

 

 

 

 

 

0

 

 

 

 

 

0

100

200

300

400

500

dbcache in 1000000 bytes

nsslapd-cachememsize and nsslapd-cachesize

The nsslapd-cachememsizeand nsslapd-cachesizeparameters determine the size of the entry cache, which caches each entry that has been accessed in memory. The nsslapd- cachememsize determines how many bytes of entries can be cached in memory. The nsslapd- cachesize parameter determines how many entries can be cached in memory. These parameters are described as follows in the HP-UX Directory Server configuration, command, and file reference. Refer to the document for more information.

nsslapd-cachememsize:

This performance tuning attribute specifies the cache size in terms of available memory space. The simplest method is limiting cache size in terms of memory occupied. Activating automatic cache resizing overrides this attribute, replacing these values with its own guessed values at a later stage of the server startup. Attempting to set a value that is not a number or is too big for a 32-bit signed integer returns an LDAP_UNWILLING_TO_PERFORM error message

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