Enforcing minimum ulimit values

You can set the minimum ulimit values that are based on the system resource availability for the optimal usage of resources by a directory server.

A directory server enforces minimum ulimit values such process data size, process virtual memory, and process file size that are considered important for running the server.To enforce minimum ulimit, a server checks if the ulimit values for the current processes are greater than or equal to the ulimit values specified in the configuration file. If the ulimit values for the current processes are lesser than the specified values, the server sets the ulimit values of the current processes to the specified values.

On Linux™ or UNIX™ operating systems, resource limits are defined for each user. When a process is started, the process inherits the resource limits set for the user context under which it was started. For example, if the idsslapd process, is started under the root user context, the idsslapd process inherits the resource limits of the root user. The inheritance occurs even if the process switches user contexts as the idsslapd process does. The idsslapd process switches the user context to the DB2® instance owner when need arises for the idsslapd process to take on the resource limits of the DB2 instance owner. In such case, the idsslapd process must be started while the DB2 instance owner is logged in.

In IBM® Verify Directory, version 6.2 and later, the directory server uses the ulimit values that are set in the configuration file sets them for the current processes. To modify the existing ulimit values, you can modify the entries under the cn=Ulimits, cn=Configuration DN entry. For example:

dn: cn=Ulimits, cn=Configuration
cn: Ulimits
ibm-slapdUlimitDataSegment: 262144
ibm-slapdUlimitDescription: Prescribed minimum ulimit option values
ibm-slapdUlimitFileSize: 2097152
ibm-slapdUlimitNofile: 500
ibm-slapdUlimitStackSize: 10240
ibm-slapdUlimitVirtualMemory: 1048576
objectclass: top
objectclass: ibm-slapdConfigUlimit
objectclass: ibm-slapdConfigEntry