openldap server load serving sendmail access map

[curtis <curtis@vesn.com>]

We are looking at migrating to LDAP as part of the architecture of our
hosted e-mail product.

As a test we started by making the access map served by LDAP.  The
sendmail gateway is running on an Ultra 2 w/300MHZ proc with sendmail
8.12.5 compiled with openldap.  The LDAP server is a Ultra 2 w/dual 300MHZ
procs and also runs PostgreSQL (with minimal load).

Even after "optimizing" the access map query for simplicity (which lowered
the load), slapd is consuming roughly 50% of the CPU.  The query has been
simplified to:

Kaccess ldap -T<TMPF> -1 -v sendmailMTAMapValue -k 
(&(sendmailMTAMapName=access)(sendmailMTAKey=%0))

The prior query which consumed even more CPU (but not substantially more) was:

Kaccess ldap -T<TMPF> -1 -v sendmailMTAMapValue -k 
(&(objectClass=sendmailMTAMapObject)(|(sendmailMTACluster=${sendmailMTACluster})
(sendmailMTAHost=$j))(sendmailMTAMapName=access)(sendmailMTAKey=%0))

The load on the sendmail server averages around 100 processes.  The CPU
load on the LDAP server is more than that of the sendmail server.  While
I would expect more overhead for the LDAP solution based on the flexibility
and all, it seems disproportionately high.

The load seemed slightly better when I bound slapd to one processor, although
that could have been a slight difference of load between the unbound test
and the bound test.

Any input would be appreciated as an LDAP architecture would solve some
headaches we have as well as lend itself to an overall better architecture.

Thanks in advance,

  -- Curt
  

Curtis Wilbar
Virtual E-Services Network, Inc.
curtis@vesn.com