For many years, several French Ministries have entrusted Samba with the role of authentication for Windows desktop machines – using Samba’s Domain Controller capability.


As modern versions of Windows began phasing out the NT4 Domain Control protocols, it became imperative for the French Ministries to upgrade to Active Directory. Thanks to the long-standing success they had had with Samba, the Ministries were keen to continue to use Samba, this time as an Active Directory (AD) Domain Controller (DC).

However, the French Ministries faced a problem: the new AD domains would need to be combined so that a single domain serves a whole ministry, not just a single site. This meant that Samba needed to upscale.

Samba was successfully operating in the smaller ministries of the French Government, however, scaling from a thousand users up to 100,000 users for the ministry of Finance was a new challenge that required Catalyst’s Samba experts.


Simply adding more hardware was not an option. Testing had shown that some databases were dangerously full, changes to the Samba AD DC codebase needed to be carried out carefully, and diligently, by experts.

Catalyst and Tranquil IT, in France, collaborated to provide an expert open source solution.

The Catalyst Samba team broke the work into parts:

  • Replacing the TDB NoSQL database layer under Samba with the 64-bit LMDB.
  • Reworking the LDAP server to be memory efficient when returning the whole DB.
  • Reworking and restructuring the server process model to allow efficient parallel processing of requests.
  • Repacking the data in the database in a more efficient format.
  • Removing poor algorithms and data structures in data replication.

At all stages, tests were carried out to measure progress and address hot-spots and bottlenecks. We used a performance test tool (traffic_replay), written at Catalyst and contributed to Samba, to provide a realistic traffic load.Samba was able to operate with 300,000 accounts.

Going forward, Catalyst continues to collaborate with Tranquil, and support the French Ministries with as they advance with Samba.