Red Hat Directory Server B.08.00.02 for HP-UX Release Notes and Supplemental Instructions

4.3.2 Tuning Database Performance
Three major parameters affect Directory Server performance: nsslapd-dbcachesize,
nsslapd-cachememsize and nsslapd-cachesize. Chapter 14, "Tuning Directory Server
Performance" in the Red Hat Directory Server 8.0 Administrator's Guide contains detailed information
about how to configure these parameters. In addition, the Red Hat Directory Server 7.1 for HP-UX11i
v2 Integrity System Performance Tuning and Sizing Guidelines contain detailed information about
sizing and performance tuning guidelines.
For Red Hat Directory Server 8.0, you must configure the Maximum Cache Size parameter,
nsslapd-dbcachesize, in combination with the Memory Available for Cache parameter,
nsslapd-cachememsize. If not, you might experience serious degradation in database
performance.
The following are the recommended settings for these parameters to tune the Directory Server
for better performance on an HP-UX system.
NOTE: The recommendations made in this section are based on Directory Service processes
that are tuned to use only one heap arena. For more information, see Section 4.3.2.1 (page 30).
• nsslapd-cachesize
The parameter nsslapd-cachesize corresponds to the Maximum Entries in Cache
label on the Directory Server Console screen.
The default setting for the nsslapd-cachesize parameter (-l for unlimited) is appropriate.
• nsslapd-dbcachesize and nsslapd-cachememsize
The parameter nsslapd-dbcachesize corresponds to the Maximum Cache Size label
on the Directory Server Console screen. The parameter nsslapd-cachememsize
corresponds to the Maximum Entries in Cache label.
Tune the nsslapd-dbcachesize parameter and the nsslapd-cachememsize parameter
values to a maximum combined value that is less than or equal to the maximum data segment
size (maxdsiz or maxdsiz_64bit) for each user process. Set the nsslapd-dbcachesize
and nsslapd-cachememsize parameters using the Directory Server Console.
Use the following formula to keep the maximum combined size less than or equal to the
maximum data segment size:
(nsslapd-dbcachesize) + (nsslapd-cachememsize) <= maxdsiz (in bytes)
where
nsslapd-dbcachesize Specifies the database cache size available for storing
database indexes and database related data.
nsslapd-cachememsize Specifies the maximum amount of memory allowed in cache
memory to store the cached database entries.
maxdsiz Specifies the maximum data segment size for a process (the
kernel parameter maxdsiz or maxdsiz-64bit). This must
4.3 Postconfiguration Tasks 29