Here's my opinion as a phd student in the systems area:
I believe it has absolutely no relation with ease of use of the operating system. As 40hz mentioned, at this level everyone could learn any of the OSs with ease.
For the guys around me, it seems to be a combination of several factors:
1 - there's a significant larger body of work for unix/linux (more people are using it, which makes others change too). example: my experience is that the software available from recent years of the Symposium on Operating Systems Principles
(the top conference in the Systems area) is mostly prepared to be ran in linux (despite much of it being cross-platform).
2 - we do much stuff that builds on industrial work (I'm thinking of Apache Cassandraw
or red hat infinispan
) for which it is easier to find support for the linux platform.
3 - we build some stuff for the industry, which prefer to receive stuff for their platform, typically linux.
4 - our processing grids are in linux (using Condor High-Throughput Computing Systemw
). I don't even know if there's anything comparable in windows.
5 - I have this notion that for those who work lower on the stack (kernel level?), it's either harder or impossible to do it in Windows due to being a closed platform (I have no experience in this and may be wrong, though).
6 - much of our experience during the university is directed at linux/unix.
7 - the availability of the tools we use (gnuplotw
are the only ones that occur, but there are many others): almost everything is an apt-get away from being installed, and if necessary we can install them in the servers to run with larger datasets. In windows, they are either harder or even impossible to install.
For the reasons above, frequently people use either linux or mac for their desktops, and linux for the servers. It is also frequent to go to meetings with other universities and find the whole room filed with macs. Last year's SOSP was here in Lisbon and I attended it, and my experience was that in general mostly only the people working at MS research use Windows and the percentage of people using mac is much larger than in the general population.
Having some kind of unix on the desktop simplifies the interactions with the servers (in our case, we have about 28linux and 1dual-boot (linux+windows), without taking into account the computing grids which are all linux). I have in the past used windows with cygwin to achieve a similar result, but felt that I was trying to "patch" windows making it look more like linux instead of using the real thing, and eventually had to change.
There's a notable exception to everything I said above: there are a few guys in our research group who had a few microsoft scholarships some years ago. Those guys have built stuff for windows for those projects and are still using it today as their main desktop.
Also, this applies only to the Systems area. There are other areas which I suppose are not as tied-in to linux since their tools are more windows-centric. (I'm thinking of the people-machine interface guys or information management. But I may be wrong