They use Debian GNU/Linux on 12000 machines scattered across the country. At DebConf11 there was a presentation given about how updates to the software are done in a single night remotely. The presentation mentions a rescue system they built in case something goes wrong. They do the normal testing followed by tests on 300 accessible clients and finally the whole set. They have a variety of clients some as small as 256MB RAM and 256MB storage to 4gB RAM. They have some custom packages and they polish the Debian packages to remove all unnecessary bytes like documentation. A messaging system notifies systems updates are available and the clients poll in a staggered and randomized pattern to spread the load out through the night. Systems that are in use 24×7 have a manual polling function. To trap defective installations, watchdog timers grab applications that fail to load and re-install packages in real time. They customize the distributions so that different types of clients and different application groups are all handled by the APT package manager.
This system has been running reliably for more than five years.
Again, this shows the extreme flexibility of Debian GNU/Linux and the reliability that can be achieved even for a nation’s whole healthcare system. These clients handle authentication, billing, medication, drug interactions and physician’s reports. They can function off-line but normally report to central servers. It also shows that what Munich is attempting to achieve can be done in a very complex system. As I have claimed many times, with GNU/Linux all problems are soluble.