RRD
From Just Solve the File Format Problem
RRD, the round-robin database is a format which stores timeseries data.
It's often used to show recent server status details (load, memory usage, bandwidth usage, etc).
The file is a fixed-size rung-buffer, so it only shows a fixed amount of history.
The magic of this file is "RRD\0" (52 52 44 00).
