Directory server does not restart after an unclean shutdown

Issue

The Red Hat Directory Server process ns-slapd won't restart after an unclean shutdown (for example, due to fencing in a cluster) when there is a process with same PID that the directory server process had before it was terminated.

The log file /var/log/dirsrv/slapd-*/errors contains entries similar to the following:

[29/Oct/2010:10:37:16 +0300] - Unable to start slapd because it is already running as process 6752
[29/Oct/2010:10:37:16 +0300] - Shutting down due to possible conflicts with other slapd processes