Finally a chance to test my backups

2012-11-13 21:46:00

Restoring from Time Machine

I've always been pretty "okay" about making backups. For years now I've been pulling drive images of both our Macbooks every month or two and both our systems run hourly backups to our NAS. Huzzah for Time Machine! Well, this weekend I got the chance to test our backups!

Having been bitten by the MMORPG bug after watching to much of SAO, I decided to save a lot of time (and money?) by closing the tab with worldofwarcraft.com and by reinstalling Warcraft 3. A few years back my brother-in-law Hans had given me the game for Christmas, so I still had the discs lying around. But! They're for PPC Macs only and obviously my Macbook has an Intel processor. Luckily you can download a Univerisal Binary version of the game through Battle.net (Blizzard's online store etc), after entering your CD keys. Which i promptly did.

Turns out that the whole Warcraft 3 game is a Universal Binary, except the bloody installer! WTF Blizzard?!

The solution is easy, yet stupid: install Snow Leopard (Mac OS 10.6) onto an external USB drive, which still has Rosetta (OS X's way to run PPC code on an Intel system). Everything went fine and I got the game installed. But when I tried to reboot to my Macbook's internal drive, I was greeted by the dreaded blinking question mark. Fudge! ( =_=)

The boot drive had gotten corrupted along the way. I have no clue whatsoever why, but it did. The only course of action, after I couldn't get the full disk encryption to open up, was to re-image the drive and restore from backups. The first part was easy: hook up my backup drive, boot from USB install stick and use Disk Utility to re-image. But then came the restore from Time Machine. 

As a Unix admin I was over thinking the whole process! I was afraid that, if I were to simply reconnect the Time Machine backup drive, the TM software would erase everything and overwrite it all. So instead I tried to use the good old Migration Assistant, which usually is a great idea. But no matter what I tried, it failed: MA wouldn't see my backups over the network and they wouldn't show up when connected locally over USB either. Turns out there are two good reasons for this:

  1. MA is meant to migrate from another system and because the backups were for this system, MA was ignoring them.
  2. TM backups made over LAN have a different structure than TM backups made onto a locally connected drive. 

Turns out that what I was afraid of, really is the right way. So here's the course of action that works:

  1. Re-image the drive, or do a clean install.
  2. Verify that the basic restore works properly.
  3. Use this command to temporarily enable the showing of hidden files in Finder.
  4. Configure Time Machine to connect to your original backup location. 
  5. Start a backup, which will first do a full inventory of what's there.
  6. When the actual file transfer starts, cancel to save time and space.
  7. Enter Time Machine. Browse to your last good backup date+time.
  8. Select your home directory and select all directories you want, including Library.
  9. Press restore and watch in awe as the counter of files quickly rises.

It could be that your restore borks once or twice, because a file is being locked by a running process. Most likely this is a cache in Library, or a plist locked by iCloud syncing. You could temporarily turn off all syncs and remove the offending files.

In my case, over 126.000 files were restored ringing in over 32GB.


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