Time machine fails to backup

Exact same problem! My old backups from all the back in 2010 only total 981.34GB, its says that the required new back-up estimates 606.7GB additional space required. Looks like its trying to creat an entire new back-up set. Anyone have any suggestions?

Same problem here. I’m running Mountain Lion. The disk I’m using for TM backup has 3.48GB of available space left.

I’ll try to repair the disk and then, if this doesn’t work, I’ll try re-formating and starting from scratch.

P.

Octavio@Promounts wrote:

Time Machine is telling me:

"The backup disk ran out of space unexpectedly. Time Machine will try to make more space available by removing expired backups during the next scheduled backup.

Open Time Machine preferences to select a larger backup disk or make the backup smaller by excluding files."

Something is happening to cause a backup that's much larger than the initial estimate. Just what that is, we haven't figured out.

Try deleting the partial backup, per #A10 in Time Machine - Troubleshooting.

Then Repair the backups, per #A5 in the same link.

Then Restart your Mac and try again.

I would expect it to erase the older files to make space for the new ones

If there isn't room for the estimated size of the backup, yes. The problem here is, the estimate was too low (and it may be trying to do a full backup, instead of just the new version of OSX and default Apple apps).

And If I erase it manually, It doesn't garantee that the files that have never changed, hence are not in the newer backups will be backed up again and may be lost forever.

The first backup to an empty drive will be a full one; everything on your system.