With the recent release of Lion I decided to upgrade my desktop from Snow Leopard client to Lion Server and at the same time migrate the Snow Leopard mac mini server over to it.

According to the combination of a knowledge base article and the migration instructions Chapter 3 page 24 this should be easy. It was not.

The knowledge base instructions say in step 2-7

Open “Install Mac OS X Lion”. Note: In order to install Lion Server, the Server app must be in the same folder as the Install Mac OS X app. If you just purchased Lion Server, these items should be in the Applications folder on the startup disk.

Click continue and agree to the software license agreement if you agree.

Click the “Show All Disks…” button.

Select a blank disk on which to install.

Click the Customize button.

Select the Server Software package.

Unfortunately that isn’t true. It only works if you are already running Lion Server!!! Here is what you need to do.

Assuming you have a disposable Snow Leopard client on volume A and have a blank volume B.

1. Boot into Snow Leopard client.
2. Use disk utility to erase volume B
3. Download both the Lion Client app and the Lion Server app from the app store.
4. They will be place in you /Applications folder
5. Run the Lion Client app, when asked press “Show all disks” then select install on Volume B.
6. Unlike what Apple say the customise button will stay greyed out and it will ignore the Server app.
7. During the install ignore the option to migrate (This is a client only migration).
8. Once Lion Client is installed run the Server App to install the server component
9. Copy the Lion Client app and the Lion Server app from the volume A /Applications to the new Lion Server /Applications directory.
10. Use disk utility to erase volume A
11. Run the Lion Client app, when asked press “Show all disks” then select install on Volume A.
12. This time what Apple say will be true. The customise button will be enabled and you will be able to select the Server component to install.
13. Connect the mac mini in target disk mode and during the install you will be invited to migrate from another server.

This guide to hosting Lion software updates on a Snow Leopard Server is correct and useful.