SteamDrv.sys: virtual filesystem
This just in from Valve, relating to this recent post:
The Steam filesystem driver is tool we use to have games see .gcf files as if they were just loose files on disk (a virtual disk). It’s a great bit of software that lets developers quickly have their game up and running on Steam – this way Red Orchestra didn’t have to change any code in order to use the cache files, it’s just handled transparently for them. It’s only loaded when launching Red Orchestra (and in the future, other Steam games that don’t write to the Steam API directly), and doesn’t have anything to do with DRM.
Being able to access your games from anywhere you log on is a big feature of Steam that isn’t going to change.
As well as easier development, the drive system should help reduce the amount of files that need to be duplicated from the GCF, which currently ranges from entire games (e.g. Darwinia) to 200-odd Megabytes of binaries and other data for Half-Life 2.