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Time Machine thinks "Latest Backup" is same as current version even though its not?

540 Views 11 Replies Latest reply: Dec 23, 2012 2:22 PM by GaryKing RSS
GaryKing Level 1 Level 1 (5 points)
Currently Being Moderated
Nov 15, 2012 11:10 PM

I've noticed an interesting thing with Time Machine and how it compares the current version of a folder with the Latest Backup version. I have a folder with a single text file. For some reason, when I change the text file, then go to Time Machine in the folder and go backwards in time, it will skip over the Latest Backup snapshot as if it's the same as the current version, when clearly it's not because I just changed a file in the folder.


Is this expected behavior (as in, does this happen to you guys as well) or is something wrong here? It doesn't seem right that Time Machine would think that the current version (which I changed after the last backup was mde) is the same as the previous version of the file in an older snapshot.

iMac, OS X Mountain Lion (10.8.2), 3.2 GHz Intel Core i3, 16 GB RAM
  • John Galt Level 7 Level 7 (33,010 points)

    Two possibilities, the first is obvious: TM only backs up once per hour.


    The second is that depending on the app you are using, it may retain its own "version history". For example, nearly all new Apple apps such as Preview and Pages do. If you wanted to revert to a previous version in them, you could do so without TM. If you were to restore a previous version of a Pages document for example, it might be restored with its version history intact. I did not consider that possibility until reading your question. It might be interesting experiment for you.


    For graduate level research such as this, I recommend Apple Support Communities contributor Pondini's Time Machine FAQ.

    MacBooks  iMacs  iPods  AirPorts, OS X Mountain Lion,  27 years Apple!
  • John Galt Level 7 Level 7 (33,010 points)

    Sure, I'll try this. Can you explain what you mean by "perform manual backups", and what you are using to create or modify the .txt file? Thanks.

  • John Galt Level 7 Level 7 (33,010 points)

    OK, done.


    I created a text.txt document containing the words "Version 0". I saved it to the Desktop, closed it and selected "Back Up Now" from the Finder.


    Waited for that to complete, opened the test.txt document again, modified it by adding the words "Version 1", saved it, closed it and selected "Back Up Now" again.


    Repeated that twice more, so the end result was a Text.txt containing the words "Version 0", "Version 1", "Version 2", and "Version 3".


    I expect that I should now have three versions from which to choose to restore, all from different times, plus the latest one still on the Desktop.


    Creation and backups now complete, so the next step was restoration:


    From the Finder, I used "Enter Time Machine" and verified that I had four different recent times from which to choose. I chose the original text.txt document and elected to "keep both files". It restored the original, which I opened and verified it contained nothing but the text "Version 0".


    I repeated this for the subsequent version. I opened that one and confirmed it contained the words "Version 1".


    I repeated this for the subsequent version. Now I have three restored text.txt documents, plus the one on the Desktop.


    I opened all four text.txt documents and stacked them as shown in the following screenshot:


    Screen Shot 2012-11-16 at 2.57.37 PM.png



    Screen Shot 2012-11-16 at 3.12.37 PM.png


    Conclusion, no surprises that I can determine.


    Is this what you had in mind, or was there something I did that was different from what you need?

    MacBooks  iMacs  iPods  AirPorts, OS X Mountain Lion,  27 years Apple!
  • John Galt Level 7 Level 7 (33,010 points)

    So, after performing a manual backup to ensure the backups are up-to-date, edit the text file. Then, go to Time Machine for the text file's folder. Click the "back arrow" to go back in time. Does it skip the "Latest Backup" and instead jump back in time by TWO snapshots, or does it go back to the immediately preceding snapshot (as it should)? For me, it does the former, where it goes back TWO backups even though the text file was JUST changed, when it should only go back once.


    After editing the text file, upon immediately entering Time Machine it shows "Today (Now)". Selecting the back arrow shows me the previous backup. No surprises.


    However, I tried something else. I edited the text file, then selected "Back Up Now". I then selected "Enter Time Machine". It shows "Today (Now)". Then, I clicked the back arrow once. Time Machine jumped to two backups ago. I then clicked the forward arrow once, upon which it showed the subsequent - and latest - backup. One more click of the forward arrow shows me "Today (Now)".


    Having done this I re-read your original post, and now I understand what you're talking about


    I think that is what you described, and yes it seems to me it shouldn't do that.


    To summarize, it seems like a minor bug that manifests itself in the initial "back arrow" user action resulting in a Time Machine display of the backup preceding the latest. Apple should fix this.

  • John Galt Level 7 Level 7 (33,010 points)

    From what you describe, it seems I have the same problem. My last post describes only one way to make it occur, but for all I know a different course of events could lead to multiple "jumps" backward with just one click of the back arrow.


    I did this on an iMac but I doubt it is limited to them. If anything, I would be less surprised if this occurred on a laptop Mac that saves Time Machine backups locally, and I haven't tested it on one of those.


    As long as Time Machine saves my backups reliably I'm pretty satisfied, but this is an apparent bug that should probably be fixed.

  • Pondini Level 8 Level 8 (38,710 points)

    Yes, the arrows don't always work properly. 


    Time Machine 101 says, "If you don’t know exactly when you deleted or changed a file, you can use the back arrow to let Time Machine automatically travel through time to show you when that folder last changed." 


    I've seen the arrows do that sometimes, and sometimes if you select a file or folder in the Finder window they sometimes do it for the selected item, but often they don't.  Usually, it just goes back or forward to the previous or next backup.


    I suspect the addition of Local Snapshots in Lion may have confounded some of the the workings of the TM browser (whether they're actually in use or not), since it's essentially "merging" two different types of backups, but that's just speculation.  I'm not sure it was all that reliable in Snow Leopard.


    I submitted a bug report during beta testing of Mountain Lion on May 11.  There's been no response yet.


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