Our experiment (LHCb, not to be confused with the collider, called the LHC) looks for specific types of particle collisions. The rate of the collisions determines the frequency of sampling the sensors, and the number of sensors (and the number of bits read out from each sensor) determines the size of each sample. But with a combination of some really fast electronics and a large cluster of general-purpose servers we end up getting this rate down to somewhere between 150 to 300 MB/sec. This is (designed to) read out about 8-9 hours a day for 9 months a year. The design was quite interesting, mainly because at each level, you had to have a team that had people with deep knowledge of detectors, physics, electronics, and computer systems to decide what to retain, how to retain, and how to discard what. I've been told that it's been a long time since we just read out everything that came out of a detector and analysed it later. (IANAP)