MTMFS consuming an entire CPU core and fans running full bore with Lion
To track down the issue you may have to dive into fs_usage or other tools that capture filesystem activity as it happens.

Normally, I have seen minor corruption issues on a filesystem (or bugs in the code - it's hard to tell / hard to reproduce this issue) as the cause of this. In practice I can't get it to fail again after cleaning the existing local backup.


sudo tmutil disablelocal
reboot the Mac in safe mode (which runs fsck and many other helpful and potentially irrelevant tests and checks for corruption)
reboot the mac normally
sudo tmutil enablelocal