I've tried checking my system drive using both touch /forcefsck and fsck from a DVD boot of Ubuntu, and both times it's been done remarkably quickly; like a few seconds for a 101 GB partition. Is that... normal?
This is being done due to some slightly odd behaviour on my computer -- a disappearing GRUB, and the failure of the computer to boot beyond powering up once or twice. The filesystem is well-established (a partition on a 500 GB drive), and the computer works normally when it boots, so I was trying to fsck for drive errors.
I would expect that a 100+GB drive should be taking longer than a few seconds. Somewhere closer to a minute would probably be more like what you should see.
A clean FS on a partition of that size should be checked in a span closer to minutes not seconds.
The answer to the question is going to vary based on a number of parameters. How fast the drive is, how much data is on the actual filesystem, and what condition the hard disk is in are all going to lend to the speed with which a fsck is performed.