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Re: Index for objectclass does not work...

>> PS: During the first search, the disk is heavy used (iotop) by writing
>> from slapd.conf ... why it - should only read ...?
> This does not make sense. slapd should not *write* to slapd.conf.

Soryy, the correct sentence is: "During the first search, the disk is
heavy used (seen with iotop) by writing from slapd, why  - it should
only read ...?"
I apologizes for this mistake!

> You should probably learn how to use strace to find out what really happens
> on your system.

I also used strace to catch the problem, but i did not find where the
slapd write to disk. It seems, it comes via set up the futex write
locks?  I'm not a kernel programmer and the code from openldap is hard
to read. But strace I use for several years to find errors, it was
also the first choice for me, to find the error. It is not a normal
file that will be written...

This behavior can be reproduce:

=> Large Database (eg. 500.000 objects/DN's)
=> put the one (same) Objectclass to >100.000 objects/DNs
=> turn of logging
=> start iotop (+ hit "o")
=> search for this objectclass and look what will happen during the
first search with your disk

> You should also install the same LDAP database and the same
> config on another physical server to see whether it behaves equally there.

I checked this problem on several machines, openldap versions (2.4.11,
2.4.21, 2.4.23) and Distribution (Debian 5, and Opensuse 11.1 and

I investigated a lot time till now to find the error, but nothing helped ...

> Good luck with your troubleshooting,