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I Recently bought a 2Tb external drive and configured time machine on my OS X 10.6.8 iMac. It started by making a full backup (approximately 1.6 Tb). Fine. I see a series of hourly incremental backups have run (a few hundred Mb each) A week goes by. All is good I have about 400Gb free on the backup disk. Suddenly it wants to make another 1.6 TB full backup. Disk full error. This implies that weekly (and I now assume, monthly) backups are not incremental. Is that correct?

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marked as duplicate by ChrisInEdmonton, Dave M, Tog, Moses, Raystafarian Apr 23 '14 at 16:53

This question was marked as an exact duplicate of an existing question.

I read that article, but that's not the behavior I am observing. – Mr. Bill Apr 1 '14 at 17:53
No, that is not normal behavior. Something caused Time Machine to no longer recognize your current machine as the same for those backups. Probably going to need to wipe it and start over. – Thebluefish Apr 1 '14 at 18:03
Seriously? in service for 7 days and it needs a reformat? Some reliable backup. You know I went to Berkeley with Waz and have been a mac bigot for years, but I find myself increasingly disgusted with their products. – Mr. Bill Apr 1 '14 at 19:14
@Mr.Bill I think (hope?) he meant wipe the backup from the time capsule and recreate a fresh backup, not wipe the machine. – Ƭᴇcʜιᴇ007 Apr 1 '14 at 20:12
I'm using an external 2Tb hard drive, not time capsual. I don't mind reformating the external drive, there isn't anything except the backups on it, but I am certainly not going to wipe my internal startup drive at this point. – Mr. Bill Apr 1 '14 at 20:21

Time Machine backups are all incremental once the first full backup has been made. But the system isn't at all smart about dealing with name changes. If you rename a directory, Time Machine will treat the change as if the old directory was deleted and a new directory was created with all the same files in it. Since it considers the directory to be new, fresh copies of everything under it will be made.

Changing the owner or permissions of a file will also trigger the creation of a fresh backup copy even if the file contents were not changed. Changing directory permissions does not trigger fresh backups of everything underneath, however.

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Hmmm... All I've done this week is edit a few photos in Canon Photo Professional. I did change the name of one photo but no folder names. Even if photo professional was backed up in it's entirety along with all the picture files on my drive it still wouldn't equal the amount of space time Machine is asking for. – Mr. Bill Apr 1 '14 at 19:24

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