Time Machine: 17+GB backups? Really?

[scaredpoet]

Seriously, there is no way that 17GB or more of data has changed on my iMac within the hour that the last Time Machine Backup was completed. This was never the case under Mavericks. And yet here is Yosemite, backing up multiple gigabytes of data every time a backup is initiated. Over and over again. And it's SLOOOOW. Sometimes taking well over an hour to complete.

Is there any way to find out what exactly Time Machine is finding that's unique, and backing up every time? I have less than 300GB on my local storage, and my 4TB Time Machine drive is starting to fill up all of a sudden.

 

[BenTrovato]

I had a 40gb backup fire away today on my MBA. I have no idea how that would be possible. No files were copied or deleted. I was only browsing and typing emails over he past few days. The backup an hour before was less than 300mb.

Interestingly enough the free space on the 1tb capsule is always 368gb free, it never changes from that amount. Starting to think something is fishy with the technology.

 

[oMc]

Are you using a virtualization product, such as VirtualBox, Parallels, or VMware?

 

[rockinwaggy]

IIRC, Macbooks (maybe Desktops as well, not sure) now store old/deleted files locally to be transferred to Time Machine at the next backup, thus why your backup size was so large. I imagine your disk usage suddenly dropped after your latest backup too when it cleared off all of the transferred data.

I think it was an addition to Mavericks, maybe even ML. Not sure as I never use Time Machine after SL which did not have that function.

Screenshot for verification. It's of Yosemite, but the functionality is the same as before.

Edit: Looks like it's been there since Lion (the Windows ME of OS X). Apple page here for confirmation >> http://support.apple.com/kb/HT4878

 

[kappaknight]

Mmm, well, this does happen in Mavericks. Every once in awhile Time Machine will say they need to create a brand new backup because the old one was no longer stable.

I wonder if the "new" process is that it'll just do it without warning you. (I hope not, but that may be what's happening.) Most people won't check how old their backups go back to as long as there is a copy of it on the network.

 

[scaredpoet]

Are you using a virtualization product, such as VirtualBox, Parallels, or VMware?

Nope, using none of these.

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IIRC, Macbooks (maybe Desktops as well, not sure) now store old/deleted files locally to be transferred to Time Machine at the next backup, thus why your backup size was so large. I imagine your disk usage suddenly dropped after your latest backup too when it cleared off all of the transferred data.

In my case (an iMac) there was no change to disk usage, other than the external Time Machine volume wasn't grinding away anymore until the next backup. Not sure why there would be use of a local Time Machine cache as the iMac hadn't gone to sleep and the drives never disconnected. Oh well. I may just turn automatic backups off until the final release of Yosemite.