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time machine not backing up system files

I have discovered that Time Machine is not (and apparently has not been for some time) backing up system files (Applications, Utilities, System and Library). What's going on? They are not excluded in the options. Anyone have this problem and know of a solution?

iMac, OS X Mountain Lion

Posted on Nov 30, 2012 1:50 PM

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Posted on Nov 30, 2012 3:17 PM

If you have more than one user account, you must be logged in as an administrator to carry out these instructions.


Launch the Terminal application in any of the following ways:


☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)


☞ In the Finder, select Go Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.


☞ Open LaunchPad. Click Utilities, then Terminal in the icon grid.


Triple-click the line below to select it, then drag or copy into the Terminal window — do not type — and press return:


sudo defaults delete /Library/Preferences/com.apple.TimeMachine.plist SkipSystemFiles


You'll be prompted for your login password, which won't be displayed when you type it. You may get a one-time warning not to screw up. If you don’t have a login password, you’ll need to set one before you can run the command.


Reboot and run a backup. Check that the previously excluded files are now included. The backup may take much longer than usual.

43 replies
Question marked as Best reply

Nov 30, 2012 3:17 PM in response to LDMartin1959

If you have more than one user account, you must be logged in as an administrator to carry out these instructions.


Launch the Terminal application in any of the following ways:


☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)


☞ In the Finder, select Go Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.


☞ Open LaunchPad. Click Utilities, then Terminal in the icon grid.


Triple-click the line below to select it, then drag or copy into the Terminal window — do not type — and press return:


sudo defaults delete /Library/Preferences/com.apple.TimeMachine.plist SkipSystemFiles


You'll be prompted for your login password, which won't be displayed when you type it. You may get a one-time warning not to screw up. If you don’t have a login password, you’ll need to set one before you can run the command.


Reboot and run a backup. Check that the previously excluded files are now included. The backup may take much longer than usual.

Dec 1, 2012 10:10 AM in response to Linc Davis

Linc Davis wrote:


It happened because you, or someone using your computer, added any of the folders /Applications, /Library, or /System to the TM exclusion list. You were then presented with a dialog asking whether you wanted to exclude all "system" files. You confirmed.

Ummmm. No. That would make sense if: 1) this computer has multiple users (it doesn't, just me), and; 2) if the system folders had been added to the exclusion list (they weren't). So, it's something else.

Dec 1, 2012 10:22 AM in response to Linc Davis

I know that I never put it there. And it was not showing up in the excluded list. And I never went into the property list to edit it (wouldn't have had a need to). I am not using a third party app to modify the Time Machine settings, but I do have a third party system mantanence app installed. There are no settings in it that I see for affecting the Time Machine function so it shouldn't have done anything to that. Plus the system files were missing from before I installed the app. While I suppose it's possible it did something to the Time Machine settings, I can't imagine that it would have deleted the backed-up system files that were already stored in the Time Machine....

Dec 3, 2012 10:35 AM in response to Linc Davis

I also just realized that Time Machine is not backing up some key files I need backed up. They are in the Library, under Application Support. I have excluded applications from being backed up, because that just takes up room unneccesarily (I can re-load applications, and many of them come with the Mac anyway). But I want the data files (Lotus Notes archive, etc.) Anyway, I tried the command in Terminal that you recommended above. Here is the reply that I got:


Domain (/Library/Preferences/com.apple.TimeMachine.plist) not found.

Defaults have not been changed.


Any idea what that is about?


Thanks!

Dec 3, 2012 11:36 AM in response to WendyRobin

WendyRobin wrote:


I also just realized that Time Machine is not backing up some key files I need backed up. They are in the Library, under Application Support. I have excluded applications from being backed up, because that just takes up room unneccesarily (I can re-load applications, and many of them come with the Mac anyway). But I want the data files (Lotus Notes archive, etc.) Anyway, I tried the command in Terminal that you recommended above. Here is the reply that I got:


Domain (/Library/Preferences/com.apple.TimeMachine.plist) not found.

Defaults have not been changed.


Any idea what that is about?


Thanks!

You could just navigate to the folder directly and look for it to confirm it's existance. Then at least you'd know if you just made an error in the process or if you have some other issue in play.

Dec 3, 2012 12:53 PM in response to LDMartin1959

I'm not sure I'm following your suggestion. I can see one of the data files that I want to backup in my library on my hard drive, for example my Lotus Notes archive database. But when I open up the time machine backup on the removal disk, that file doesn't exist. I have not excluded it from Time Machine backups, so I can't figure out why it doesn't show up on the time machine backup disk.

Dec 3, 2012 1:01 PM in response to WendyRobin

The plist in question is under the main library folder (not the user libary folder). If you made an error in following the original instructions posted by Linc Davis, you may have ended up in your user Library. I still don't understand how my system files got excluded either but deleting the plist as speicified solved the problem for me. Hopefully will for you as well. If you are not sure you are navigating to the correct library, let me know by email and I will put together a step-by-step series of screen shots for you so you can double check that you are in the correct place.

Dec 7, 2012 5:53 PM in response to Linc Davis

I have the same symptoms as LDMartin1959, but the cause is slightly different and may be worth bearing in mind for others with this issue.


In my /Library/Preference/com.apple.timemachine.plist:


The SkipSystemFiles key is and as far as I know always has been <false/>


My issue was caused by the ExcludeByPath key. Looking back at the com.apple.timemachine.plist files that are in my TM backups:


1. After a clean install of ML, there is no ExcludeByPath key, but there is:

<key>IncludeByPath</key>

<array>

<string>/Applications</string>

<string>/Library</string>

<string>/System</string>

<string>/bin</string>

<string>/private</string>

<string>/sbin</string>

<string>/usr</string>

</array>


2. Some later (after install of Microsoft Silverlight perhaps?) the IncludeByPath key is still there but there is a new key:

<key>ExcludeByPath</key>

<array>

<string>/Library/Application Support/Microsoft/PlayReady</string>

</array>

TM continues to work well. The PlayReady directory is emply on my Mac - I assume because I have not downloaded any DRMed Silverlight media.


3. Two days ago TM stopped the backup of 'system' files, because:

a) the IncludeByPath key is no longer in the plist, and

b) ExcludeByPath is now:

<key>ExcludeByPath</key>

<array>

<string>/Library/Application Support/Microsoft/PlayReady</string>

<string>/Applications</string>

<string>/Library</string>

<string>/System</string>

<string>/bin</string>

<string>/private</string>

<string>/sbin</string>

<string>/usr</string>

</array>

So not surprising that there is no backup of system files!


What has made this change? I have no idea! I don't have any evidence that is directly due to Silverlight. My suspicion is that some application is directly modifying the plist (no doubt for good reasons), but is doing it wrongly! Or is TM doing it wrongly (it does rewrite the plist at every backup)?


Simplest solution is probably to delete the whole plist, let TM recreate it and reenter my own exclusions.


I will try and set up some monitoring of changes to the plist.

Dec 7, 2012 7:17 PM in response to Gilby101

A little more information. The CoreServices API has the call CSBackupSetItemExcluded which includes a parameter to excludebypath. So there is a legitmate method for applications to ask OS X to modify the com.apple.timemachine.plist to add (and remove) items from the ExcludeByPath key. My suspicion now is that there is a bug in the OS X code implementing this API call.

Dec 8, 2012 11:30 AM in response to WendyRobin

As an update, I have "fixed" the problem, although I have no idea why the change I made would have fixed it. The user library that I wanted to have backed up was pinned to my finder sidebar. It was not being backed up, even though it had not been excluded. I removed it from the sidebar, and on the next Time Machine backup, it was included. Makes no sense, but that honestly seems to be what happened.

time machine not backing up system files

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