I'm not a fan of Time Machine. I run into more TM bugs than I ever saw with cranky old Retrospect -- and I get less notification of problems.
Today I found a critical laptop hadn't been completing it's TM backup for about 2 days. It was showing a common, unhelpful, error message "time machine an error occurred while creating the backup folder".
David Alison's Blog has the answer for a standalone time machine. Turn off TM on the affected machine. Then navigate to your TM backup folders and look for something like "2010-02-01-134046.inProgress". Delete the "inProgress" file.
This doesn't work for Time Capsule though. TC won't let you delete the inProgress file. I couldn't find any report of a fix, save dragging the actual machine specific TC sparse disk image to the trash and starting over. (The official response to all similar problems, by the way, is to wipe the entire TC disk and redo ALL machine backups).
What worked for me was to turn off Time Machine on all the TC clients. Then I restarted the AirPort and then turned TM back on for the troubled machine. The backup chugged away for a while, and then it resumed.
- Freeing up Time Capsule space – and documentation for Time Machine and Time Capsule
- Fixing the Time Machine / Time Capsule 10.5 "Backup volume could not be mounted" bug