Small tour of Atlas
Atlas is a computer cluster situated in the basement of a university building near the Max Planck institute in Hannover. Since the ceiling is not very high we do not have a single picture showing everything but this picture already gives you some impression of the cluster (and also shows two busy admins):
caption="Atlas - two rack aisles"
The Atlas cluster is mainly used for searching for gravitational waves by analyzing the data of the detectors GEO600 (Germany)
, Ligo (United States of America)
and Virgo (Italy)
What are gravitational waves?
Accelerating masses emit gravitational waves similarly to how electromagnetic waves are emitted by accelerating charges. These masses can be, for example, two black holes that collide in distant space. Albert Einstein predicted the existence of gravitational waves in 1916 in his general theory of relativity, however, only since the 1990s has technology become able to detect them. Gravitational wave detectors try to measure length differences caused by gravitational waves with the use of interferometry.
What does the ATLAS cluster do?
In brief, the predicted and calculated data patterns are compared to the actual data from the detectors with the help of ATLAS' computing power. One hopes to find data patterns that support the theory of gravitational waves and make the measureable directly. So far, the influence of gravitational waves on other masses has only been detected indirectly through observations of binary pulsars.
Technical equipment of the cluster
In total, we currently have 5 aisles with 1680 computes nodes (each has 4 CPU cores), 32 data servers, and 12 very-high-reliability storage servers in use. The cluster encompasses a overall storage capacity of 1.38 PetaByte
; which is 1 447 035 GB. The network is linked with cables that have a bandwith of 10 GB per second, which is more information per second than fits on a dual-layer DVD.
If you are interested in knowing more about the technical side of the cluster, take a look at the technical overview