Wednesday, March 4, 2009

Windows 7 Shadow Copies

Since Windows Server 2003, Windows has had a feature called shadow copies. Basically, this allows you to get back to previous versions of existing or deleted files. The feature was later enhanced in Vista to make the "system restore" feature. Namely, the system takes snapshots of important system files your computer needs to boot by creating "restore points". At any point in the future you can revert to such a restore point. This can be because your system stop rebooting or you just noticed that game demo included SecuROM and is still installed even if the game demo no longer is.

The feature works has advertised however, there was no way in Vista to know how much disk space this feature was using or could use. Windows 7 includes new configuration options that control these settings.



Tim said...

Now I'm curious, why is SecuROM so evil?

pjulien said...

Well, not evil, but impolite.

The problem is that it installs without asking the user. Afterward, when you uninstall the game, it won't be uninstalled.

Furthermore, even if you download the SecuROM uninstaller from their site, it doesn't get rid of all the files and registry entries.

The registry entries have null characters in them so they can't be deleted manually with regedit. You have to write some code or find a utility to do it for you.

The file name it enters use high Unicode characters meaning the files can't be deleted from the Windows shell or command line without either:

a) Writing some code
b) knowing that some characters represent the "." even if it doesn't show up on the file name. So for example, doing "del *" will return an error saying the files don't exist. But doing "del *.*" will actually delete the files.

Cataphract said...

You can control the size of the storage in vista: vssadmin resize ShadowStorage /For=ForVolumeSpec /On=OnVolumeSpec [/MaxSize=MaxSizeSpec]

pjulien said...

Yes, I know, I was pointing out that you can now do so from the GUI in Windows 7.