Re: multiple subordinates and shm_key - not a good idea

[Howard Chu <hyc@symas.com>]

matthew sporleder wrote:
> I am using openldap 2.3.21 and bdb 4.4.20 (both compiled 64-bit) on solaris 10.
>
> It seems that using multiple shm_keys in slapd.conf with many
> subordinate databases results in unusable data.  I'm about to try and
> re-import with the same shm_key on all of the subordinates.  (ugh!)

Shared memory is managed directly by the BerkeleyDB library, not 
OpenLDAP itself. Whether a database is subordinate or not in OpenLDAP 
has no impact on BerkeleyDB; BerkeleyDB hasn't got any clue of what the 
calling application is doing with those databases and keys. All 
BerkeleyDB knows is that you're accessing multiple distinct database 
environments. Each BDB environment must be completely separate. When 
you're using BDB with plain environment files, you must configure them 
all in separate filesystem directories. When using shared memory regions 
the requirement doesn't change; every environment must be separate. 
Using the same shm_key for all the environment regions is guaranteed to 
fail.

It's not a good idea to try to use shared memory without reading the 
standard Unix documentation on shared memory. See the ipcs manpage for 
information on diagnosing shared memory usage. Notice that a single BDB 
environment is composed of many shared memory regions, occupying a range 
of keys starting from the one you specify and on upward. You can't use 
consecutive keys in your configuration because the subsequent keys are 
already in use.
--
  -- Howard Chu
  Chief Architect, Symas Corp.  http://www.symas.com
  Director, Highland Sun        http://highlandsun.com/hyc
  OpenLDAP Core Team            http://www.openldap.org/project/