LDAP hangs requiring slapd stop and deleting __db.00* files

[Abhishek Daga <abhishek@ostech.biz>]

We have been running a virtual, multi domain mail server with the 
following configuration.
Redhat 9, Postfix, Courier, openLDAP, Spamassassin, Razor, squirrelmail, 
amavis, maildrop.
openLDAP is used for authentication.

Facing the following issues with openLDAP from time to time.

a) OpenLdap seems to get locked up every once in a while. i.e. While the 
process is running, it fails to authenticate.
Because process is still running, our monitoring system, Monit, does not 
recognize that as a failure.

Then we need to stop slapd. delete the /usr/var/openldap-data/__db.00* 
files, restart ldap for it to start working again.


b) When the server load becomes high, 4 to 5 then authentication is 
irratic. It works sometimes and sometimes it does not.
When server load became high to the tune of 16/18, ldap failed 
authentication.

What could be the reason for the above? anyone faced similar issues? I 
wouldnt mind looking at commercial alternatives to openLDAP if the above 
problems can be sorted out. ofcourse the best would be if the problem 
lies with us and not the software as fixing it would be easier than 
reinventing the ldap wheel.

Any and all help is always appreciated.

thanks!
abhi