You buy a NAS for silent, always-on storage. It sits in a corner, humming quietly, doing its thing. Then you install Docker. Then Syncthing. Then a few containers.
Suddenly the HDDs never stop. Seeking, spinning, clicking. Not occasionally - constantly. At 2am you can hear it from the next room.
This is what happened, why it happens, and how to make it stop.
What's Actually Causing the Noise
Mechanical HDDs make noise when the read/write head moves. The more random the I/O - small reads and writes scattered across the disk - the more seeking, the more noise. Sequential writes to a single file are quiet. Random I/O across thousands of small files is loud.
