On Apple’s support website for Time Machine, it claims:
With Time Machine, you can go “back in time” to restore files, versions of files, or your entire system.
I ended up testing this out recently with workable, but less than stellar results. I have kept notes for the past month or so on all the things that got messed up or lost because of my attempt to use Time Machine to restore my system. It all started when I had chosen to update an app. Performing the update turned out to have been a mistake. I went from a fully functional app to one that had put up a pay-wall between me and the functionality I’d previously had for free. Re-installing the old version didn’t restore the functionality either. Somehow, it knew that some component of the newer version was still there somewhere on my system. After trying to hunt it down, I finally decided to put my Time Machine to work and do a system restore – a drastic measure – but it was an important app. What I’d read about Time Machine assured me that it was like “going back in time” – making your system the way it was at some selected date in the past. I’d had some experience with such systems on unix & linux machines (the tivoli backup server I used at a couple different places where I’ve worked) but I had not done a full restore before – usually just individual files or folders. I’d also used Time Machine for such smaller recoveries too and it works like a charm for that. So I felt confident. I would restore my computer to the state it was 3 hours ago – well before I’d performed the update. First of all, the restore took about 36 hours in total – including 9 hours of re-importing email and a number of hours rebuilding thumbnails in iPhoto. Then, there were all these losses of settings. I still run into various settings that I have to re-do, and other users may have other custom settings that would also be lost, so I consider this an incomplete list – just a sample of what to expect if you decide to do a system restore via Time Machine. They are in roughly the order in which I discovered them:
- Time Machine scarily asked me to “set up my mac” using an assistant (which seems shouldn’t be necessary – since it had been setup before).
- Keychain Access forgot where my custom keychain database file was.
- Had to re-import all my email.
- Function key mappings were gone (KeyRemap4MacBook syspref settings).
- Had to re-install flash.
- My dock item for the app I created with Xcode, “BeaconOSX” turned into a question mark, so I had to manually fix it.
- Pressing Volume up/down once ramped the volume all the way – can’t remember how I fixed this one.
- The dictation system preference setting got turned off.
- My custom clock format settings got reset (I like to see the date & day of the week in my menu bar).
- Had to re-log into FaceTime.
- iWork asked me for my Serial Number when I tried to run Numbers! (luckily I still had the box)
- iPhoto had to rebuild my thumbnails.
- iPhoto asked me if I want GPS locations with my photos.
- Mail.app sound settings reset. (I had turned off the send mail sound.)
- Printer presets were gone – and I had a BUNCH of them.
- Control-scroll was unset in the accessibility System Prefs.
- All my custom keyboard shortcuts were gone from the Keyboard App shortcuts in System Preferences.
- Left pane in Finder windows was reset to default – I had to re-add all the folders I’d been keeping there.
- Screenshots settings gone (default folder, no shadow added, etc.).
- Terminal settings gone (e.g. transparency, window title, etc.).
- Folder actions were reset, so I had to re-add my scripts to a variety of folders.
- Reverted my “Allow apps downloaded from” security setting in System Prefs to “Mac App Store and identified developers”
- Turned Safari’s “Correct Spelling Automatically” setting back on
- Sys Prefs->Sound Effects->”Play user interface sound effects” got re-activated
- Sys Prefs->Accessibility->Audio->”Flash the screen…” got de-activated
- The license code for my paid copy of “Audio Hijack Pro” was lost and I had to re-unlock the software out of trial mode
Finally, after your restore is done, Time Machine will complain about not being able to connect to the backup drive because it is connected to another system. I believe all I had to do was restart my backup drive, but you may need to start a new backup from scratch. It is of course a lot of little things, the most annoying of which was the lost print presets, but they all add up. Would I do it again? Yes. The old app was restored to a point before the update and I regained all the lost functionality. However, if Time Machine is billed as a system to restore your system to the way it was at some point in the past, then they’ve got a little polishing to do before it truly does do that. In most cases, people are restoring system that have crashed and getting anything back makes one fall down on their knees and praise God. Time Machine is an awesome system for that, but if you’re restoring your system to get just a little bit of something back – like in my situation – know the annoyances and headaches restoring from Time Machine will inflict. At the very least, save your printing presets on an external drive and afterwards, go through this list and restore your lost settings manually. It might also be a good idea to do some screen-caps of your Terminal preferences.