I never saw an announcement, and the FAQ has no mention of it. However when I went to install a game today it asked me which SteamLibrary I wanted to install to.
As someone who's list of owned steam games is larger then the capacity of my fast hard drives this has always been an issue.
Install onto my fast disk drive, but only have the current big titles, or use a slower drive that can hold more?
Since a lot of the games need the performance I am using my Fast, but Small, drive. Unfortunatly that meant even the games that did not require fast disk access were forced to take space alongside my more important AAA titles, or just not get kept on my PC at all.
Todays discovery has changed all that, so I am in the middle of seperating my lesser titles onto my slower drives.
Since it took a bit of experimenting to figure out how to transfer the files without requiring a full download, these are the steps that seem to work. Normally just having the files in the right directory and restarting steam is all that is required, but it seems steam still only looks at the primary install location. It will not spot the files present in the additional drives.
From withing Steam
1. Install a new title, which will allow you to chose a new drive and create a new SteamLibrary on it.
Either let the game download completely, which will create the full file structure needed, or manual create the folders.
From within Windows Explorer
2. The full structure needed is (Drive
3. Manually copy the game folders from your current Steam Install folder into the new library. (eg, I am copying from G:\steam\steamapps\common\Bastion to H:\steam\steamapps\common\Bastion)
From withing Steam
4. Right Click on the title you just copied, and choose Delete Local Content
This will uninstall the game from the original location.
5. Right Click the title you just deleted, and choose Install Game. Choose the new drive from the list (for me it is H:\SteamLibrary)
6. Steam will now start to prepare the install and will go a new stage called Discovering existing files
7. Complete. Repeat steps 3 to 5 for each game you want to move.