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Re: Tuning OpenLDAP and Scalability

Here are a few things you might want to consider:
Upgrading to the latest openldap.
Read the docs on tuning your backend.
(You've specified neither version nor backend)
Throttle/tune your java connection pools, timeouts, etc.
Figure out who's dropping what.  openldap normally doesn't drop
anything- it just churns through ops as they come in.  (I suspect your
jvm's are set to timeout before all of these ops can finish)
Tune your operating system to fix connection drops/increase io performance.
Buy larger hardware.

On 2/20/06, Ramseyer, Ken <ken.ramseyer@lmco.com> wrote:
> One of our systems consists of approximately 500 hardware units (nodes),
> and our applications use CORBA and Java's RMI for inter-process
> communication.  We have one master LDAP (slapd) server for reads and
> writes running on one hardware unit, plus we have a replicated slave
> LDAP (slapd) server for reads running on another hardware unit.  slurpd
> runs on the master to keep the slave up-to-date.
> The master slapd server's CPU utilization is normally less than 1% in a
> steady-state system.  During initialization, multiple applications on
> each hardware unit register their CORBA and RMI object references with
> the master slapd server.  When shutting down, multiple applications on
> each hardware unit un-register their CORBA and RMI object references
> from the master slapd server.  The master slapd server works fine if we
> reset (shutdown and restart) a few hardware units at a time; we see the
> master slapd server's CPU utilization rise for a few seconds and then
> return to normal as objects are being deleted and added to the LDAP
> database.  Even resetting 50 hardware units at a time seems to work
> fine.  However, if we reset over 75 hardware units at a time, the CPU
> usage of the master slapd server shoots up to 99% for a minute or two,
> and we can actually lose object deletions or additions.  As we approach
> the resetting of 75 hardware units, the master slapd server becomes
> overwhelmed with simultaneous requests to un-register and register
> object references.
> How can the master slapd server in our system be tuned to handle well
> over 100 hardware unit resets at a time?  In other words, how can
> OpenLDAP be tuned to handle a large burst of simultaneous ldap_delete
> and ldap_add operations from multiple applications running on multiple
> hardware units?
> Ken R.