Newsletter Avril 2008

Implémentation d'OpenLDAP à l'Hôpital de la Tour par Michael Lawson, IT Manager (en anglais)

“Some years ago we were faced with a need to replace our aging Windows NT PDC/BDC servers. The "obvious" approach was to migrate to Microsoft's Active Directory, but instead we chose OpenLDAP for three reasons: a) the licencing: it is freely modifiable and redistributable; b) the commitment to open standards; c) the absence of a large commercial organisation controlling its direction (and the risks that might arise from this).

Our Windows NT PDC / BDC infrastructure also provided DNS and DHCP services; we therefore had to migrate these network services as well.

Our network is composed of some 300 plus PCs, about 50 servers, and operates over several sites, maintaining NT Trust Relationships with several other Windows domains. There are approximately 600 network accounts. The project was therefore neither insignificant in scale nor complexity; furthermore the hospital is a 24 hours 7 day a week operation: we had to ensure that downtime would be minimal and limited to a quiet period late in the evening.

Linalis managed the project, breaking it down into several phases, with the migration of DNS and DHCP services initially, followed by network authentication using OpenLDAP / Samba to replace our old PDC / BDC. Phasing it in this way proved to be a wise approach, and although the total elapsed time from completion of the first phase to being able to shut down our old Windows PDC / BDC, was considerable, the work was done transparently without measurable disruption.

More recently we wanted to take advantage of various enhancements to OpenLDAP and its management tools; however the initial implementation was on a commercial distribution of Linux which unfortunately did not lend itself up to upgrading: with this in mind we recently switched distributions.

We used the opportunity of this upgrade to restructure the servers and now have two Debian machines each hosting a Debian VM, with replication of DNS, DHCP and LDAP data between the VMs which perform the roles of PDC / BDC. So far this has proved to be robust and stable; it should also prove very straightforward to re-host the services on new hardware, should the need arise.

This type of upgrade, while simple in principle is none-the-less complicated in the detail: failure to prepare thoroughly inevitably leads to a high profile outage of network services, and a high pressure scramble to restore to the old configuration. Fortunately we managed to avoid this scenario as a result of adequate analysis of the requirement, and of making sure we had a small (but valid) test network using an identical network address structure on which we could run test imports of the LDAP directory, of DNS and DHCP data until we felt we had a recipe that would work faultlessly.

The upgrade took place a few weeks ago when we migrated DNS, DHCP and OpenLDAP data all together late one evening, on a fully transparent basis, retaining the network identity of the old PDC / BDC so that the client machines would not be impacted (we kept the same IP addresses for DNS). The preparation - which was very much a joint effort with us doing the work and Linalis providing the coaching - paid off handsomely: there were no user calls the following morning complaining of difficulty connecting, including those who are dependent on external domains with Trust Relationships.

You would not be reading this article unless we were grateful to Linalis for their assistance with this exercise. I think it is important to say a few words why.

Anyone with knowledge of Unix / Linux, will know that these operating systems impose a tough discipline: it is no good just clicking in a pretty GUI (which usually hides the details) and hoping for the best: you need a good understanding of the system. Whilst the learning curve is steep, the advantage is that a properly configured network is robust, fast and reliable. If you lack Linux skills (and most IT departments are light in this area), an external consultant who is a real partner is a huge advantage: complex and apparently risky projects can be achieved at modest cost with the appropriate transfer of skills.

Using Linux to run your network has been a viable alternative for a long time; there's no longer any excuse for not doing it !

Le Département de l'Instruction Pulique (DIP) vient d'annoncer qu'il va remplacer sur les postes de travail les logiciels propriétaires Microsoft par les logiciels libres. Cette migration concerne l'ensemble des Ecoles du Canton de Genève et sera effectué d'ici à la fin de l'année. Pour télécharger l'article de la Tribune de Genève, cliquez ici.

OpenOffice 2.4 est disponible. Cliquez ici pour télécharger.

La Commission Européenne prévoit une utilisation accrue de l'Open Source, pour en savoir plus, cliquer ici.

Sun commence à certifier Ubuntu sur ces serveurs, plus d'information cliquez ici.

Linalis est heureuse d'annoncer l'arrivée d'une formatrice spécialisée depuis plus de 10 ans dans la réalisation de site Internet. Engagée à temps pariel, Dr Cathy Needham, a rejoint notre équipe et propose ces services dans "L'écriture de sites Internet" (1 day) et le "...Ces formations sur mesure sont organisées en fonction de la demande, n'hésitez pas à nous contacter pour plus d'information.

Notre compagnie soeur, Léman Games, va à nouveau organiser durant l'été deux sessions intensives de cours de Jeux Vidéo pour les 12 – 20 ans.