macosshutdown
My rMBP 15" just shut down by itself when idling, screen turned off.
When I rebooted it, I checked the Console to see why it shut down, and found this message: 10/27/12 1:21:36.000 AM kernel[0]: Previous Shutdown Cause: -108
What is Shutdown Cause -108?
In general a negative shutdown codes are related to the hardware issues. Unfortunately the precise meaning of the codes is not publicly documented, so the best is to back up your data and give it to the repair.
We have a small group of 2012 and 2013 retina MBP and only one in the group has the -112 restart cause logged when it freezes in a hard manner. The rest have never once froze hard or shut down/rebooted spontaneously.
No diagnostics from Apple show a specific failure - the SSD has been tested extensively and doesn't have any other errors that fsck lists or corrects (other than the typical minor and correctable filesystem corruption that a hard reboot causes).
In the last 3 months, it has logged two -112 restarts and two -128 restarts.
If you paid for AppleCare - take it in and get it repaired. If you have to pay for a repair, it will likely be the $300 to $400 flat rate repair where they send it in for factory diagnostics and overhaul.
Best Answer
According to this page, Shutdown Cause -108 seems to be due to a lack of memory.