I encountered something interesting today with Time Machine. I'm using a Synology 212j NAS that Time Machine backups to for 3 Macs; a iMac, MBP, and a MBA. Today the MBP began to backup like usual but instead of backing up a few hundred MBs it began to backup the ENTIRE hard drive of about 52GB of data. I checked the backup folder on the NAS and the .sparsebundle for the MBP was gone! I ran DaisyDisk on the folder location and it only found the two .sparsebundles for the iMac and MBA. What's the deal? This kinda defeats the purpose of backing up, I never know when the .sparsebundles will disappear. Update: the iMac and MBA both performed backups just fine, about 300MBs each. I checked the NAS capacity and theres 85% of free space so space isn't a issue.