Comment 1 for bug 874826

I had something very similar affect me. From my (internal) bug report (which we haven't investigated yet):

"...one device's CPU whisper directory had 2 okay files, one partially-written file (maybe with a bad header as well?), and several zero-byte files. While in this state, metrics collection seemed to not be working. Metrics were coming in (possibly getting stored to the okay files, but I can't remember), but the problem didn't correct itself even after I removed the partial file and restarted daemons all over the place. Completely removing both nodes' whisper directories allowed things to work again once all the whisper files got created again."

In hindsight, maybe it was the zero-byte files causing the problem? It doesn't sound like I tried removing those.