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The triumph of Linux as a supercomputer OS

Operating systems on supercomputers used to be custom-made affairs, but this has changed. These days, Linux has become a popular choice for supercomputers. But how popular? You may be surprised. maintains a list of the fastest supercomputers in the world. A new list was published yesterday (it happens twice a year), so we took the opportunity to go through the list and find out what OS the top 20 supercomputers are using.

It took some work, but the results are interesting.

Linux usage among the top supercomputers

When we list the OS for each of the top 20 supercomputers, the result for Linux is very impressive:

19 of the top 20 supercomputers in the world are running some form of Linux.

That’s 95%! And if you just look at the top 10, ALL of them use Linux. The ratio may change a bit if you look at the complete list (it has 500 entries) but we simply didn’t have time to go through the full list and find out the OS for each computer. However, there can be little doubt that Linux is a dominant OS among the top supercomputers, and most likely across the field. (Update: Linux has an 88.6% share of the top 500 supercomputers.)

Operating system used by the top 20 supercomputers
Rank Computer Vendor Operating System
1 Roadrunner IBM Linux
2 Jaguar (Cray XT5) Cray Linux (CNL)
4 Pleiades SGI Linux (SLES 10 + SGI ProPack 5)
5 BlueGene/L IBM Linux (CNK/SLES 9)
6 Kraken XT5 Cray Linux (CNL)
7 BlueGene/P IBM Linux (CNK/SLES 9)
8 Ranger Sun Linux
9 Dawn IBM Linux (CNK/SLES 9)
10 JUROPA Bull SA Linux (SLES 11)
11 Franklin Cray Linux (CNL)
12 Jaguar (Cray XT4) Cray Linux (CNL)
13 Red Storm Cray Linux (UNICOS/SUSE Linux)
14 Shaheen IBM Linux (CNK/SLES 9)
15 Magic Cube Dawning Windows (Windows HPC 2008)
16 GPC IBM Linux
17 Encanto SGI Linux (SLES 10 + SGI ProPack 5)
18 EKA HP Linux
19 Juno Appro International Linux (Redhat)
20 Jade SGI Linux (SLES 10 + SGI ProPack 5)

The complete June 2009 list (but without OS information) can be found on the site.

Looking at this list, it becomes clear that prominent supercomputer vendors such as Cray, IBM and SGI have wholeheartedly embraced Linux.

Judging from the results for the top 20, it looks like SUSE Linux (SLES) is a very popular option, although what version of Linux a supercomputer is using isn’t always specified.

In a few cases Linux coexists with a lightweight kernel running on the compute nodes (the part of the supercomputer that performs the actual calculations), but often even these lightweight kernels are based on Linux. Cray, for example, has a modified version of Linux they call CNL (Compute Node Linux).

Why Linux?

IBM used to focus on its own mainframe UNIX system, AIX, but has been a strong proponent for Linux for years now. When IBM started its Blue Gene series of supercomputers back in 2002 it chose Linux as its operating system.

We think the following quote from Bill Pulleyblank of IBM Research (from this 2002 ZDNet article) nicely sums up why IBM and many other vendors have chosen Linux:

We chose Linux because it’s open and because we believed it could be extended to run a computer the size of Blue Gene. We saw considerable advantage in using an operating system supported by the open-source community, so that we can get their input and feedback.

In short, it looks like Linux has conquered the supercomputer market almost completely.

What are your thoughts on this, and what does this mean for Linux?