[Kolab-devel] Kolab and OpenPKG

[Dieter Kluenter]

Hi Martin,

Martin Konold <martin at max.kde.org> writes:

> Am Freitag, 23. Mai 2003 09:16 schrieb Dieter Kluenter:
>
> Hi Dieter,
>
>> > This is the reason why I think that it is possible that introducing
>> > direct LDAP support for postfix is maybe the wrong solution for the
>> > potential scalability problem.
>>
>> A well indexed directory server is much faster then parsing a hashed
>> file.
>
> Really? Any pointers to some benchmarks? I was expecting that the overhead of 
> client/server is always higher than a hashed file. Basically I expect a 
> hashed file to be memory mapped and the access to be basically instant 
> because the hashes directly lead to an index in an array.

AFAIK there are no benchmark data or even suitable benchmarking test-suits
available for openldap. But I can give you some information of a test
I did with sendmail, looking up local recipients.

The system, 900 Mhz AMD, 768 MB Ram, 2 scsi discs, 
sendmail-8.12.7
openldap-2.1.17 with berkelydb-4.1.25, database bdb, indexing
sendmailMTAMapName, sendmailMTAHost, sendmailMTAKey,
sendmailMTAMapValue, sendmailMTAAliasValue, objectclass, uid, cn. 
loglevel 0, 
cachesize 3.145.728, configured in DB_CONFIG
databases on /dev/sda 
transaction log on /dev/sdb
mail log on /dev/sdb
mail spool on /dev/sda
sendmail and openldap on a single machine,
slapd started with parameter "-h ldapi://" that is, unix socket only.
sendmail configured to hold a persistant connection to the directory
server. 
At random generated 30.000 users
db_stat showed that 99% of indexed attribute values were kept in
cache.

A perlscript generated 2 e-mails addressed to this 30.000 users (just
headers and subject, no content). I steadily encreased the mail
production, sendmail managed a maximum of 60 mails per second.
Openldap never had more than 20 waiting requests, the average
answering time was 0.2 seconds, lowest 0.02, highest 1.2 seconds.
In fact, the bottle neck was sendmail, not openldap. The same would, in
principle, apply to postfix as well.

-Dieter


-- 
Dieter Kluenter  | Systemberatung
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