Mass Storage Room Computers
The Mass Storage Room (MSR) represents the digital brain of a LIGO interferometer. Analog photodiode signals from the interferometer undergo treatment and analog-to-digital conversion on rack-mounted equipment that occupies a room adjacent to LIGO Hanford's laser and Vacuum Equipment Area (LVEA). The digitized signals then travel to the MSR on optical fibers and undergo digital filtering and processing on the computers that you see in the panorama. All of the contents of these racks are new as of 2013, the MSR having been completely upgraded as part of the Advanced LIGO program.
On the left wall of the room viewers can see two red tanks that contain a fire suppression chemical. Moving rightwards, the racks contain data servers, timing equipment (including an atomic clock and a GPS timing receiver), rack-mounted PC's known as "front ends" that handle the interferometer controls, disk storage arrays, additional computers for packaging the data, and UPS backup systems on the far right. On the rear side of the racks (not visible) are many meters of color-coded cable that carry communications between the front end computers.