21:33 - Saturday, 19 April 2014

Fseventsd Is At 100%CPU When Time Machine On External Hard Drive Is Connected

When I connect an external hard drive with storage space and also time machine on it, in activity monitor it shows a process call fseventsd taking up 100% CPU and it slows down my computer to a halt and i have to unplug and do a hard restart. How do i connect without this fseventsd?

fseventd is a critical system process that tracks file reads and writes. Disabling it can be tricky and has some serious side effects.

Why not run the command fs_usage to see what is being read and by what to know if you just need to wait out spotlight or some filesystem check or instead have a data or hard drive problem where this won’t go away even after several hours.

Basically, you’ve come into the hospital and asked “Hey doc, how do I kill my immune system? All this pus from some infection is disgusting.” The doc will want to know what’s happening, where and why. You might be right and need chemo, but it also could be something treatable with a band-aid and some bacitracin.

This solution worked for me:

In Terminal, make a directory called “.fseventsd” (mkdir .fseventsd) in the drive mounted by Time Machine, and add a file inside called “no_log” (touch no_log).

It tells fseventsd process not to bother reading the backup drive.

The annoyance ceased immediately. Time Machine backup worked flawlessly.

I found the solution on the MacRumors forums.