Since installing 10.7.2 Time Machine no longer backs up. I get the error message "the backup disk image '... iMacsparsebundle' could not be accessed (error -1)" Any ideas anyone? Update: At 5:30 pm yesterday, Time Machine started working again! Must be one of those 'back door updates'.
Further update The error recurred after I shut down the computer. I'm hoping the Time Capsule firmware update released today, will fix the problem.
Many people like to do time machine backups without ever changing anything. I like to rotate different drives in/out of my external docking station. When I rotate a ( slightly older one ) drive in I usually erase the existing partition ( thus forcing a complete new backup ... aka it takes a while ) before getting the first new backup onto that drive. I also have local backups disabled. Best advice is to make sure one is aware of the tradeoffs involved between just taking system defaults versus a custom strategy.