Server User Manual

Chapter 3. Plug-in Implemented Server Functionality Reference
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This attribute is provided only for system modification/diagnostics and should be changed only with the
guidance of Red Hat Technical Support or Red Hat Professional Services. Inconsistent settings of this
attribute and other configuration attributes may cause the Directory Server to be unstable.
For more information on database transaction logging, refer to the "Monitoring Server and Database
Activity" chapter in the Directory Server Administrator's Guide.
Parameter Description
Entry DN cn=config, cn=ldbm database, cn=plugins,
cn=config
Valid Values on | off
Default Value on
Syntax DirectoryString
Example nsslapd-db-durable-transactions: on
3.4.1.10. nsslapd-db-home-directory
This is usually applicable to Solaris only, and is used to fix a situation in Solaris where the operating
system endlessly flushes pages. This flushing can be so excessive that performance of the entire
system is severely degraded.
For users of other systems, to move the database to another physical location for performance
reasons, use this parameter to specify the home directory.
This situation will occur only for certain combinations of the database cache size, the size of physical
memory, and kernel tuning attributes. In particular, this situation should not occur if the database
cache size is less than 100 megabytes.
If the Solaris host seems excessively slow and the database cache size is around 100 megabytes or
more, then use the iostat utility to diagnose the problem by monitoring the activity of the disk where
the Directory Server's database files are stored. There are three conditions required before resetting
the nsslapd-db-home-directory attribute:
• The disk is heavily used (more than 1 megabyte per second of data transfer).
• There is a long service time (more than 100ms).
• There is mostly write activity.
If these are all true, use the nsslapd-db-home-directory attribute to specify a subdirectory of a
tempfs type filesystem.
The directory referenced by the nsslapd-db-home-directory attribute must be a subdirectory
of a filesystem of type tempfs (such as /tmp). However, Directory Server does not create the
subdirectory referenced by this attribute. This directory must be created either manually or by using a
script. Failure to create the directory referenced by the nsslapd-db-home-directory attribute will
result in Directory Server being unable to start.
Also, if there are multiple Directory Servers on the same machine, their nsslapd-db-home-
directory attributes must be configured with different directories. Failure to do so will result in the
databases for both directories becoming corrupted.