pheld

Friends, from time to time (like this morning), I find that Time Machine on various Macs around the house seems to "start at the beginning" or do what would be a major backup as opposed to just an incremental on what changed. For example, this morning, my wife's new MBP (month old) started TM on a 12GB backup, basically the entire disk.

TM has been working (successfully it would appear) on this machine since day 1. Does anyone know why TM would do this and is this normal?

thanks much, Paul

pheld

Could this be the MBP's first "monthly backup" - I think this is exactly its 1 month anniversary. So it's taking everything that's changed in the month - which in this case is everything.

Am I on the right track? thanks

BlackViper

Are you modifying any large files? Torrenting in particular can cause Time Machine to have large backups.

TM doesn't do "monthly" backups, it consolidates the hourly ones into daily and weekly versions.

pheld

No, that I know of. My wife's machine - essentially new as I said and nothing like massive files being added or changed on this particular machine.

I have noticed it occur from time to time on two other Macs - my Mini which is a music server and the family iMac. Same story with those in terms of files/usage.

I must be missing something regarding the mechanics of the backup process.

BlackViper

Could you expand on the 12 GB number you quoted? Is this a typical back-up size or just an isolated example. TM only back-ups whole files so a minor change to a large file, or minor changes to a number of files could be your issue. Re-naming a large batch of photos, for example, will result in them all being backed up again. A full backup will happen if TM thinks you have a new system, a major hardware change(HDD upgrade, major repair) or re-installing OSX. If you apply many software updates at once, this can make the next back-up larger than normal.