Forced Shutdown of rMBP - First Time in a Year!

No hardware is damaged by forced shutdowns, but it is possible for some data loss or filesystem metadata inconsistency to occur. This is true regardless of whether it is a SSD or HDD.

Computers don't write directly to the hard disk because that would be very slow. Instead, they write data to the drive's buffer cache, then write from that buffer to the actual storage media. When you shutdown normally, all the data currently sitting in the drive's buffer is written to the drive before the partitions are unmounted. A forced shutdown kills the power without writing that data to the disk, which causes it to be lost. This can be a problem if the metadata that tells your system where your files are (among other important things) is lost.

There are ways for filesystems to mitigate this problem though. Journaling filesystems such as HFS+ write the changes they make to a journal, so if power is suddenly lost and you reboot, the filesystem can simply refer to that journal and carry out the operations again until the system is consistent. There still is a risk of data corruption, but it is lessened.

This is over-simplified, but the main point is that hardware is generally not damaged by forced shutdowns.

haha you're kidding right

there are plenty times when I've had to hold down the power button to reboot on my '14 15" rMBP, no risk for issue especially with Apple's highly integrated logic board. How do you think Sleep would function without it?

Wow! I have a late-13 rMBP that suffered from "trackpadgate". The only way I knew how to fix it was to force shutdown. Luckily they fixed it eventually! Haven't had too many problems since other than a random sleep/wake issue or two recently.