OpenLDAP and Samba4

Howard Chu hyc at
Sat Apr 20 12:28:36 MDT 2013

> Date: Sat, 20 Apr 2013 16:04:46 +0200
> From: G?mes G?za <geza at>

> 2013-04-20 12:17 keltez?ssel, Luke Howard ?rta:
>> > On 20/04/2013, at 7:32 AM, G?mes G?za <geza at> wrote:
>> >
>>>>> Sorry to express my own opinion as not a samba team member or
>>>>> regular
developer (few small patches doesn't count), but instead of trying to use
OpenLDAP as a backend for samba, wouldn't be useful to try to use tdb/ldb as
the backend for OpenLDAP and to see what other changes are needed in order to
have it listen on 389/tcp and 636/tcp on behalf of Samba, something like the
s3fs setup?
>>> That's not a bad idea: enforce the ?business logic? (i.e. SAM
constraints, etc) in the actual backend database itself, rather than in the
layer between the protocol and the backend database. (We did something
similar, but much simpler, with the NetInfo backend for OpenLDAP some years ago.)
>>> However: Howard and the OpenLDAP team have invested a lot in backend
database design (see back-mdb) and I would expect they'd like to leverage
this, not just the protocol front-end.
>> >
>> > -- Luke

> Switch from tdb to mdb perhaps?

(mdb is now called LMDB, to avoid confusion with Microsoft Access mdb etc.)

This has been discussed privately. It is unfortunately not a slam dunk today 
due to concerns about 32 bit compatibility. Since LMDB works by directly 
referencing data thru a memory map, it can't manage more than ~2GB on a 32 bit 
machine. This has not been a concern to us in OpenLDAP because most server 
deployments are on 64 bit hardware these days. The notable exception, 
smartphones, rarely have databases bigger than a few MB in size.

We recognize that LMDB may not be practical for some 32 bit embedded servers 
that Samba targets. We anticipate that 64 bit ARM will replace these devices 
soon and the problem will go away.
> Cheers
> Geza Gemes

   -- Howard Chu
   CTO, Symas Corp. 
   Director, Highland Sun
   Chief Architect, OpenLDAP

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