Home Forums Mac Software Mac Operating Systems Time Machine's dated backup folders

When I look inside the TM Backups.backupdb folder (and the subsequent folder wherein the actual backups are found), I see the periodic, daily backup folders.

Can one manually, as well as safely, delete any of those dated - daily backup folders?

- While I've presently got plenty of backup space on the drive, which TM is using, I'm curious if manual deletion of old backups can be done to free space without causing unintended problems.

All I've read indicates that Time Machine automatically discards its oldest entries to free up space if its drive fills up, so unless you want to delete backups in the middle of your sequence your question may be pointless.

general rule of thumb, do not open packages unless you only intend to look, or really know what you're doing.

The principal TM folder is a ".backupdb" folder. Is that a package?

...I'm familiar with extracting from packages by "right-clicking and open package" procedure for other things, but this seems more like nested folders.

You can, but only by asking Time Machine to do it.

To do that, make sure you have an "Action" control in your Finder's toolbar. (It's there by default, but you may have deleted it. If the toolbar is showing controls as text, the text will be "Action". If toolbar controls are being displayed as icons, the icon will look like a gear. If it's not in the toolbar at all, use View→Customize Toolbar to put it back.)

Then, enter Time Machine (that is, the "star field" view). Navigate through time to the snapshot you want to delete. Then, from the Action control's menu, select "Delete Backup".

As of Snow Leopard, you cannot do this from Finder (by dragging a backup to the Trash), and you cannot even do it from the command line. Not even using sudo. (Snow Leopard introduced a feature called Mandatory Access Controls, that even root is obliged to obey. Time Machine uses this feature to protect its backup; ONLY Time Machine is allowed to delete/rename/move/modify items within the backup.)

There are rare occasions where you want to delete a snapshot before its time. One is to influence which snapshots get promoted from hourly to daily to weekly. Just delete the other contenders that would beat out the one you want TM to promote.

(Example: you've been letting TM back up every hour, and notice that the snapshots it's promoting to weekly are all Tuesday snapshots. You have a daily snapshot, created on Thursday, containing files you created on Wednesday but deleted the following Friday. Those files were not incorporated into any Tuesday snapshots. If left to its own devices, TM will therefore not put them into any weekly snapshots. To force its hand, manually delete the Tuesday and Wednesday backups that don't contain the files, leaving the Thursday backup that does. Eventually, that Thursday backup will get promoted to weekly (it being 9 days after the previous weekly backup), after which TM will continue treating Thursday as the first day of the week, until the next time time there isn't a Thursday snapshot to promote.)

But for the most part, just leave TM alone. It can delete an old snapshot to make room just as fast as it can delete one you tell it to delete manually. You don't get any performance gain by fiddling with it.

Great bits of information. Thank you for your detailed reply.

The big two offenders are iTunes Music and iPhoto Library. We periodically get users in here that were apparently bored and decided to delve into those packages and "sort things" by moving them around and mainly renaming them. Which of course makes iPhoto and iTunes totally wigg out and is a mess to fix.

I also notice apple hid ~/Library recently, for much the same reason.

But that won't stop them. Last week I had to fix two machines whose users elected to move their Microsoft User Data folders. And we've probably all seen at least ONE person that's renamed their home folder back when Finder used to let you do that.

> And we've probably all seen at least ONE person that's renamed their home folder back when Finder used to let you do that.

Never did that, but in my earliest Mac days I renamed my HD "H/D."

OS X didn't like that one tiny bit.

It's gotten over it. Doesn't mind that a bit.

It was definitely a bug. Macintosh users create way too many files with dates in their names for Apple to be squeamish about slashes.

The way they resolve that is: HFS uses colon as the path separator, so individual names are not allowed to contain a colon, but slash is OK; Unix uses slash as the path separator, so individual names are not allowed to contain slash, but colon is OK. There is a perfect symmetry there. A file named "Expenses 6/2011" is represented exactly like that, with a slash, on disk. The "glue" that binds OS X onto Unix translates the name on the fly, so that all Unix utilities see it as "Expenses 6:2011". And of course a file created at the command line as "Train 8:13" will appear in Finder (and on disk) as "Train 8/13".

If a volume named "H/D" was ever a problem, it can only have been because volume names are stored differently than filenames, and someone forgot to do the conversion there too. But it's been fixed (sparing me the hassle of submitting a bug report). I just renamed one of my volumes "H/D", and Unix was quite willing to tell me all about /Volumes/H:D.

Now, trying to name it ".HD" would be a problem, and in fact is not allowed. (At least not now. I've heard stories of people doing that in the before time.)

Thanks for the fill-in. (I noticed the slash/colon thing long ago in Finder and, particularly, in iTunes.)