I just updated from Lion and Mountain Lion on my Macbook Air 2012 w/ 8GB ram and the process diskarbitrationd is using 99% of the cpu. Any ideas of the cause?? It's really sucking the power out of the Air...
Maybe it was just that- I just am surprised it was indexing for that long, since it's not like I had just added a bunch of new files. But I rebooted and it stopped, but I'll keep an eye on it.