Time Machine Details
Several launchd-controlled daemons and property lists for preferences determine Time Machine’s behavior. The global preference file is /Library/Preferences/com.apple.TimeMachine. plist.
This stores preferences such as the Time Machine currently enabled state and exclusions. The primary daemon is /System/Library/CoreServices/backupd, which is controlled through launchd via the /System/Library/LaunchDaemons/com.apple.backupd.plist file. backupd is the main daemon that handles the actual work; Time Machine also reacts to several events. One event is time once an hour, Time Machine gathers the list of changed files and sends them to the backup disk.
The daemon that makes this happen is /System/Library/LaunchDaemons/com.apple.backupd-helper.plist launchd LaunchDaemon, by calling /System/Library/CoreServices/backupd.bundle/Contents/Resources/backupd-helper. You can change the interval in the plist file:
# defaults write /System/Library/LaunchDaemons/com.apple.backupd-auto StartInterval
-int (integer in seconds)
The default time is 3600 seconds, or one hour. Time Machine also reacts to disk mount events, in order to ask the user whether a given drive should be used as storage for backup. These disk mount events are handled by /System/Library/LaunchDaemons/com.apple.backupd-attach.plist, which looks for mount events and runs backupd-helper with an -attach switch. You can turn off this behavior by adding a key to /Library/Preferences/com.apple.TimeMachine.plist:
# defaults write com.apple.TimeMachine DoNotOfferNewDisksForBackup -bool YES
If desired, you can push out this setting with managed preferences.