Time Machine - Frequently Asked Questions

13. How are backups scheduled (and can I change that)?

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Time Machine was designed and optimized to do backups hourly

A backup will start when Time Machine is first set up, either via the Preferences window or in response to the "Do you want to use <drive name> to back up with Time Machine?" prompt (see question #21).  That starts the hourly schedule.

You can also do extra backups manually, via Back Up Now from the menubar icon (or the Preferences window if there are multiple backup drives on Mountain Lion or later), per question #34).

Sometimes the backups may not seem to be on an hourly schedule, but they are.  The Preferences window and/or menubar icon display show the completion time, but Time Machine will start the next backup an hour after the start of the previous backup, if your Mac is awake and the backup drive is available.

You cannot change the schedule within Time Machine.  You must use a 3rd-party app, or manually alter some system files.

It's usually best to let Time Machine do its hourly backups.  It was designed and optimized to work best that way, and will protect you best if you leave it alone.  When things are working properly, backups should usually be relatively small and quick (after the first, full backup, or after an OSX upgrade) -- they should not interfere with your work -- in fact, you should rarely even notice them.

You can adjust the built-in schedule, with 3rd-party apps, but it's not recommended.  Those apps don't work with Time Machine -- they schedule separately, which means Time Machine must be turned OFF via the Preferences Window, or they'll both be starting backups.

Other considerations:

  1. You may be giving up one of the main advantages of Time Machine:  when you accidentally change or delete the wrong file, or a file somehow gets damaged, the hourly backups provide a much better chance to recover a previous version of that file.

  2. If you change the backup drive on the Preferences window, that automatically turns Time Machine back ON.  As noted above, you must remember to turn it OFF, or both will be starting backups.

  3. If you have a laptop running Lion or later, turning Time Machine OFF means your Local Snapshots are also turned off.  You can turn them back on manually, via a special command.  See Question #30 for details about local snapshots, and the blue box there for instructions.

  4. If you go 10 days without a backup, you won't get a notice of that from Time Machine.  Most of the apps don't provide a warning . . . ever.

  5. Before you upgrade OSX, you should be sure the version of the app is compatible with it.

  6. Since Time Machine "thins" your backups after 24 hours automatically, keeping only one per day, doing fewer backups usually won't save much space on the backup drive.

If you still want to do this, use the free Time Machine Editor, TimeMachineScheduler, or similar apps, but study it's help and/or instructions carefully to avoid conflicts.

Early versions of Time Machine Editor (prior to version 2.5), and possibly some of the others, change one or more of the following system files, in your /System/Library/LaunchDaemons folder:

  1. com.apple.backupd-attach.plist

  2. com.apple.backupd-auto.plist

  3. com.apple.backupd-wake.plist

  4. com.apple.backupd.plist

If you can't use version 2.5 or later of Time Machine Editor, or are using a different app, copy those files somewhere safe before using the app.  Then if there's a problem, you can delete the changed/damaged ones and put the copies back.  Do not attempt to edit these yourself -- you may lose control of Time Machine entirely, and have to reinstall OSX to fix it.

Also note that if you want to resume hourly backups, use the app to change back to the normal schedule and/or turn the app OFF (check with the maker to be sure how to do that) before deleting the app.  Otherwise, the last schedule set by the app may remain in effect, in addition to Time Machine's normal schedule;  it will be very difficult to change it any other way.

Some circumstances that may alter or re-set the hourly schedule:

  1. If you do a manual backup, Time Machine will skip the next hourly backup if it's scheduled within the next 10 minutes, but won't reset the schedule.

  2. When your Mac wakes from sleep, it will do a backup immediately, unless one was done within the previous hour.  That will reset the schedule.

  3. If you change exclusions (per question #10) or backup drives, Time Machine will run a backup 120 seconds later (or when you quit System Preferences), but won't reset the schedule.

  4. Restarting your Mac will reset the schedule, but it won't run a backup immediately, even if it's more than an hour since the last one.  It will wait about 30 minutes, to avoid conflicts with other things that may run automatically, or manually by the user, after startup.  

If you're considering this because your hourly backups are too large or degrade your Mac's performance significantly, there's likely something wrong.  Doing backups less often is dealing with a symptom, not the actual cause.

  1. If they're too large, using too much disk space, see Troubleshooting item #D4.

  2. If they're slow, hanging, or slowing your Mac down, see Troubleshooting item #D2