Apple lion reinstall experience and surprise¶

Tags: python, django, apple

My year-old macbook installation was showing its age. Or rather, there were some things wrong with it:

• The original OS was 10.6, snow leopard. I upgraded it to lion (10.7) half a year ago. This was an in-place upgrade, not a fresh install. I wanted a fresh install to clean some stuff up and because it started to feel slow. I heard that a clean install would help a lot regarding speed.

• I work a lot with geographic libraries, Django and geodjango. So originally I installed everything via the kyngchaos packages. Mapnik, gdal, spatialite and so on. But after the lion upgrade, I couldn’t compile any python packages with C extensions anymore as gcc 4.0 (which everything had been build with) had been replaced by 4.2. And spatialite never would work right anyway. So I wanted to replace this.

• I used homebrew as a package manager for the gnu/unix side of things instead of macports I’d been using before. It works, but I missed some things, like Quantum GIS (QGIS), which is included in macports. I hoped to get everything python+gis related done with one package manager, in my case macports.

So I made sure my backups were OK, that my code was all committed, that my repositories were cleaned up, that all my dotfiles in my homedir were in version control and so on. Most of it was already OK, but of course there were some small things left. I’ll do a write-up later on of my backup strategy and how I handle my dotfiles and so.

Time for the actual lion reinstall. How does that work? I bought Lion from the app store, so it was downloaded and installed by my mac: I didn’t have an install DVD. Turns out to be easy: just restart and press command-r during bootup and you’ll get a “lion recovery” menu. Choose the reinstall option and it will download the latest full version and install it for you. Simple and works.

The big surprise came when the computer rebooted. I expected a dialog to set up a main user. Instead, I got the regular login screen. Ok… Logging in… Hey! All my stuff is still there! All the settings, all my documents, all my music… No need to restore backups.

So: an OSX lion restore wipes only the OS and reinstalls it. Including xcode, btw. The rest (your own data, applications, settings) is retained. Actually pretty handy.

This did mean I had to clean up the kyngchaos packages and homebrew by hand. Just a matter of deleting some directories, telling homebrew to erase itself and adjusting my paths.