Red Hat Bugzilla – Bug 195501
lmtpd group lookups bypass nscd and cause high ldap or nis traffic/load
Last modified: 2008-08-02 19:40:33 EDT
Description of problem:
The lmtpd process appears to do group lookups using getgrent() instead of
getgrnam() therefore bypassing using the local nscd cache, this causes a great
deal of network traffic and queries to ldap or nis servers. On a busy mail
server this causes mail to be slow and the load on the ldap server to rise.
There is a patch around to use a group.cache file, but it is not implemented in
Version-Release number of selected component (if applicable):
Instantly noticable in our environment when using ldap.
Steps to Reproduce:
1. Change auth mechanism to ldap client
2. restart cyrus-imapd
3. Watch network traffic and ldap queries to ldap server
I think the best work around would be to get cyrus to use nscd thereby reducing
the number or queries to the ldap server. I tried using "ldap_sasl: 0" in
/etc/imapd.conf, but this had little effect.
This request was evaluated by Red Hat Product Management for inclusion in a Red
Hat Enterprise Linux maintenance release. Product Management has requested
further review of this request by Red Hat Engineering, for potential
inclusion in a Red Hat Enterprise Linux Update release for currently deployed
products. This request is not yet committed for inclusion in an Update
(In reply to comment #1)
> This bug is seriously effecting our internal infrastructure AFAIK... Adding to
> the RHEL 4.5 list. Peter, what are the chances this can be addressed?
Perhaps we can recruit some testing from IS. :)
+ qa_ack for rhel-4.5
Mark/Nate: Can you help QE in testing this?
After investigating the issue, the proper solution is not a private caching
scheme for cyrus (proposed patch above), but using getgrouplist library call
instead of pulling down complete list of all groups. I have verified that nscd
cache is used for this call properly. Now just need to write the patch and
verify that it works correctly :).
Created attachment 137671 [details]
Asking for feedback from reporter. There are now cyrus-imapd rpm packages
available (cyrus-imapd-2.2.12-7.RHEL4.*), so I would like to ask the reporter
to provide the feedback if the network traffic and queuries to ldap or
nis server improves with these new packages installed.
Or pls provide more configuration details so I can verify your problem
(and consequently it's solution :o))
I tested the patch supplied by Tomas Janousek and this seems to have fixed group
lookup issue in my test environment so many thanks.
An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on the solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.