I got this message while testing something on my web server. I was quite baffled to find out that there was, in fact, quite a lot of space remaining.
What Is Tail?
The “tail” program is a command line utility for Linux based machines. To read the last few lines of a text file (such as a log), the command is “tail /path/to/file.log”.
However, the true power of the tail program comes when adding the “-f” argument. Now, it will show the last few lines of the file, along with anything appended to the file. Running “tail -f /var/log/nginx/error.log” shows me, in real time, the errors that are occurring on my server.
Searching For A Solution…
I read a few articles on the web about this problem, after I tried freeing up some space.
Ultimately, the problem was due to CrashPlan’s greediness (and a bug in the “tail” program).
How To Fix It… For Reals
Instead of configuring the system to have a higher value for “fs.inotify.max_user_watches”, just restart the crashplan service. Or Dropbox, or whatever it is. Just restart a service, then try running “tail -f” again (on virtually any file): if the error went away, then the culprit was that last service you restarted.