With MS Vista Service Pack 1 now available, some users have observed a non-trivial hit to their available disk space after installing the update.
What’s happening is that SP1 backs up previous versions of many components during installation, consuming quite a bit of disk space in the process. If you’re completely confident that you won’t need to uninstall SP1, you can actually reclaim that space. Vista SP1 includes an optional tool called Vsp1cln.exe which will remove the files backed up during installation. After the Vista SP1 installation completes, Vsp1cln.exe will be located in your Windows\system32 directory. You can run it by dropping to a command prompt (or press “Winkey + R” on your keyboard) and and typing Vsp1cln.exe and pressing Enter.
The cleanup utility will warn you that you’re about to make your Vista SP1 installation permanent, and prompt you for confirmation. Once confirmed, the cleanup process will begin. Again, don’t execute this file removal utility unless you’re certain that you won’t need to uninstall Vista SP1. But if you’ve created a full backup of your computer prior to installing Vista SP1 (I actually prefer to image my entire system before doing this sort of thing), this may not be much of a concern.
So how much disk space can you reclaim by running Vsp1cln.exe? Most users are reporting just under a gigabyte of recovered space, depending upon which version of Vista is installed. Your mileage may vary. And if you still need a better understanding of how your disk space is being consumed, well then you need FolderSizes.