Olefin,
Olfan wrote:By the time I took notice the log file was some 180GiB in size. I panicked, killall'ed QRecallHelper and deleted the QRecall.log so it wouldn't choke my Mac with clogged local storage.
That was clearly the right thing to do. Once the connection to the volume was broken, the helper process was useless anyway.
QRecall's pretty fanatic about logging everything it does, but even I'm having trouble thinking of anything that would generate 180GB of log data without stopping. Most logging is self-limiting: you get an error, or three, or a hundred, but ultimately the process gives up, logs one final "I've given up" message, and terminates.
The only code that will log an error and continue to plow ahead is during a repair, and that code (at least in QRecall 3.0) does limit the number of messages it logs before logging just a summary. There is also code that corrects slightly damaged data, but if the drive was dis-connected there's no way successive corrections could be successful.
So without a peak at what was getting logged, I can't offer much in the way of useful suggestions, other that what you've already done.