However, you may not want a backup every hour — the backup disk is a limited resource. If you’re regularly changing large files then Time Machine is regularly writing large amounts of data to the backup disk, and if that’s the case then you won’t have backups going back very far into the past.

So there will be lots of revisions of files that have changed recently, but nothing much from, say, a couple of months ago.

So how do you change the interval?

The standard Time Machine options don’t allow you to change the backup interval (the time between backups), but the preferences are there to be changed if you know how.

From the command line

If you don’t want to install any extra software then you can change Time Machine‘s backup interval from a shell prompt. Start up a Terminal window and then type:

sudo defaults write /System/Library/LaunchDaemons/com.apple.backupd-auto StartInterval -int 18000

The 18000 above is the required backup interval in seconds — five hours in this example. And note that the above command is all on one line.

Point-and-click

There are several full Mac OS applications out there that allow you to manipulate Time Machine‘s hidden preferences. The two most popular are Time Machine Scheduler and Time Machine Editor. I haven’t used either (being someone who leans toward using the command line), but they look like they’ll do the job. However…

My recommendation was, but is no more:

I did suggest using the Secrets prefPane to change Time Machine‘s backup interval (see below), but unfortunately that turned out to be bad advice. You can set the interval using the Secrets prefPane but it doesn’t stick. Quit the System Preferences application and start it up again and you’ll find the interval has gone back to the default of 3600 seconds.

So it seems Secrets prefPane doesn’t work for this after all! I’ll leave the rest of this article in place and perhaps someone will tell me when the problem’s fixed?

In the mean time, please use one of the options suggested above.

Here’s the rest of the original article, which at the moment doesn’t work:

I suggest you use the Secrets Prefpane from blacktree. Just download it from the link near the top of the web page, unzip it and then install it by double-clicking on the resulting file (Secrets.prefPane).

Now, when you start up System Preferences you’ll find a new preferences pane:

The Secrets preferences pane allows you to set the hidden Time Machine backup interval:

but — and this is why I recommend the Secrets prefPane – it also allows you to change all sorts of other hidden preferences in Mac OS:

which is great fun — and who knows, may even prove useful

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