[Kolab-devel] LDAP performance

[Andreas Gungl]

Hi, 
 
after having managed the import of about 18.000 addresses into our Kolab 2 
(test) server, I would like to provide some feedback and ask some 
questions. 
 
The many contacts have been added as addresses (not users). Importing via 
ldapadd was very slow. It took me more than 5 hours on our PIII-500 test 
machine with 256 MB RAM plus slow HDD. But hey, import needs to be done 
only once. :-) 
Handling the data in the admin interface is problematic, there are issues 
in the tracker (admin interface can't handle more addresses than in the 
LDAP limit AFAICT). Well, I've set up some Perl scripts to support the 
update of these addresses. So I don't have to care. 
 
The processing of queries is very different. I experience _very_ fast 
searches out of KAddressbook / Kontact (less than 0.5 sec for serveral 
names), while Thunderbird / Mozilla are really slow (10-15 sec for the 
same queries). Using TB/Mozilla, the CPU load is above 90% for quite a 
while. I think that's because of the way how those tools define the lookup 
("name plus email", but they search e.g. the givenName as well, at least I 
think so after looking at it in ethereal). 
 
Following the thread about tweaking the LDAP and DB backend configuration, 
I've set (on Kolab 2 RC 1) in /kolab/var/openldap/openldap-data/DB_CONFIG 
  set_cachesize 0 65000000 1 
  set_lg_bsize  2097152 
 
I expect it to be 64 MB cache, is that okay this way? I must admit that I 
couldn't completely follow the explanations of Dieter. Hm, I blame it to 
my English. 
Another change was made in /kolab/etc/kolab/templates/slapd.conf.template 
  idlecachesize 10000 
  sizelimit 20000 
 
That should cache ~50% of the data, while I can query all records without 
getting to the limit. Does that look fine? 
 
I'm really unsure about the config values. But changing them and trying to 
measure is not as easy as it seems in the first place, so I thought I 
might ask here. 
 
Anyway, the good news is that Kolab can handle that data quite fine. But 
if you have Mozilla LDAP clients, you will need a strong CPU. 
 
Best regards, 
Andreas 

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