It’s fairly well accepted by most commenters at this point that Time Machine may be one of the biggest features to be part of Leopard. Even those users who managed their own backup solutions – and many still do, including myself – applaud it for making […]

It’s fairly well accepted by most commenters at this point that Time Machine may be one of the biggest features to be part of Leopard. Even those users who managed their own backup solutions – and many still do, including myself – applaud it for making backups both easy and intuitive for the average end user. (I credit it for having dramatically reduced panicked phone calls from friends and family about missing files, and that alone made the effort of updating oh-so worth it.)

However, many of us would also like ways to change the frequency of its backups. By default, Time machine runs once an hour, saving a daily backup at the end of the day and a weekly backup at the end of the week. This behavior continues until the drive it was pointed to is full, at which point it begins to delete the oldest backups. Almost immediately, people wanted a way to change the frequency – even if, like me, half the reason was the annoyance of those bright-blue, flashy LED’s on the external hard drive as it spins up every hour in the middle of the night.

An earlier hint at Mac OSX Hints had users editing a .plist file to change the frequency of backups. This hack consisted of editing com.apple.backupd-auto.plist, specifically the following lines:


A change to that integer value – which is in seconds, by the way – and Time Machine would theoretically back up on your schedule, not Apple’s. However, that seems to cause more problems than it solved, in my experience. Specifically, now Time Machine backs up whenever it likes. (It seems to be about once a day, give or take an hour or so, not once every three hours, as I set it to be.) Upon inspection, it appears that the file’s permissions are broken. Repairing permissions in Disk Utility hangs, and attempting to manually do so, even on a duplicate, causes Finder to crash.
…Let’s just say that method is Not Recommended, then.

Alternatively, there is now this – Time Machine Scheduler.  Time Machine Scheduler does not meddle with the .plist files – it simply runs its own daemon to create a backup.  It can be set for any length of time between 1 and 12 hours, as well as optionally running a backup upon loading.  You have the option of either installing Scheduler and its daemon, in which case you do not need to open TMS, or simply running it from the .app when you want to make a backup. It is also fully compatible with existing Time Machine backups – the preference pane will show that Time Machine is off, but it reads the TMS-created backup and date of last backup without trouble.

There is also the option to mount and unmount the Time Machine backup drive automatically, although I have not tested this.  (I have a partitioned drive, and the other partitions are in frequent use, so I don’t bother.)


This method works very well for me, at a reliable three hours.  It takes the same amount of time to run backups, as well as to load and unload the normal Time Machine interface, and, thank heavens, it actually does it every three hours.  Why Apple didn’t include the option to change the backup frequency all along boggles me.

I will note that a third way to do this is to use Lingon to edit the plist files.  I have not tried it, but I thought I would mention it, for  those who might be interested.  How about you?  Have you tried Lingon?  Time Machine Scheduler?  Did the original .plisthack work for you?

(Time Machine Scheduler and Lingon are both free utilities, available at the links above.)

  1. For some of us, a weekly backup is more than sufficient. I wish we could pick longer intervals like that. Also, I wish Time Machine had a way to exclude folders, instead of entire drives. With a tiny bit more flexibility, they could’ve designed a backup for nearly all of us, instead of just those who don’t care what gets backed up and how often.

  2. Scott H:

    Time Machine can exclude folders just fine… go to Time Machine Preferences, click on the Options button and a sheet drops down. Click on the “+” button and use the file picker to choose whatever folders you want excluded.

    1. Thank you. Just the tip I needed to control the size of my backups.

  3. I would also like to tell Time Machine to include folders on an external drive for backing up. All of my music and photos are on an external drive and Time Machine is not dealing with this. Or is it?

  4. Also, if you really want to backup just once a week then you could turn automatic backups off (slide the main switch to Off in Time Machine Preferences) and manually trigger backups once a week by ctrl-clicking on the Time Machine dock icon and selecting the “Backup Now” menu item.

  5. Thanks, Chris, for both tips. I really didn’t see the folder exclusions–I guess it’s possible to make an interface so simple the user assumes features aren’t there.

    Is there any way to limit how much space Time Machine eats up on a drive, or does it just swallow it whole as it adds backups?

  6. Dan, Time Machine includes external drives in the backup quite nicely. There is just one point you should be aware of: If you have aliases pointing from your main drive to an external drive, they will be backuped as is and still point to the original file/folder even when you access them on the Time Machine volume. So if you want to browse/restore data from an external drive, you MUST navigate through the /Volumes/… hierarchy inside Time Machine to get to the backup(s)

  7. Scott, Time Machine will (eventually) use all the space that is available on a backup volume. The only way to limit it so it didn’t use the entire drive would be to partition the drive and use one partition for Time Machine backups and the other for whatever other stuff you want to store on the drive.

  8. jen_chan, writer SureFireWealth.com Friday, January 4, 2008

    Thanks for the tip! I haven’t really explored that feature yet since I’ve gotten so used to the old school ways of backing up my files (i.e. burning them on blank cd’s). But I appreciate articles like yours giving us a heads up.

  9. Over the holidays I decided to use RAID on my drives. After I got the H/W configured the way I wanted, I just reloaded a fresh copy of Leopard and then recovered everything else from Time Machine. I went to bed to let it do its thing and when I got up in the morning, my system was fully reloaded with all my user accounts, data, iPhotos, Mail, etc. The only difference is now my disk drives are bigger, faster, and mirrored. I am sold on the product, but would also like to see more configurability in it.

  10. Hello, I’m new to the Apple Mac interface and I have to say I enjoy it very much to be honest with you. As soon as I plugged my iMac in and switched it on. It was bye bye to my old PC and out that went through the window and nicely landed in the pile of trash in my drive.

    Now onto my question. Would it be possible for anyone to give me some useful advice for when im setting up my Time Machine on my iMac. I am using a 320gb External Harddrive as the backup drive.

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