A week ago I wrote about my investigations into System Restore on Windows XP and Windows Vista. I have since heard back from a program manager at Microsoft, who said of the Vista default disk allocation: We believe that the default value 15% is very well balanced number for the vast majority of customers. This isn't particularly useful to adjust, unless you have a very clear space constraint on your machine. How A week ago I wrote about my investigations into System Restore on Windows XP and Windows Vista. I have since heard back from a program manager at Microsoft, who said of the Vista default disk allocation: We believe that the default value 15% is very well balanced number for the vast majority of customers. This isn’t particularly useful to adjust, unless you have a very clear space constraint on your machine. However, advanced users (ItPros) would like all possible kind of control they can have, so we’ve heard requests for it in the early days of Vista. But I don’t expect much more feedback on that. Regarding the technical details of it, we’ve added it to a blog post: https://blogs.technet.com/filecab/archive/2006/11/16/identifying-how-much-disk-space-is-used-for-restore-points-in-windows-vista.aspxThat Technet blog post makes interesting reading. But before I summarize it, here’s a question: Why is Microsoft using Web log entries to substitute for actual documentation? I have the feeling that it’s because there are things that the development teams are willing to share with anyone smart enough to find their blogs, which haven’t made the cut through the documentation process because they are too technical or dangerous for a typical user. Maybe there are plans to bring this sort of information into the formal documentation later: I don’t know. The blog post referred to above starts: Beta testers and even MS employees often ask us why restore points take up so much disk space and whether this can be adjusted. I also see the opposite problem reported—testers are surprised that so few restore points are being kept on the system. The best way to see what’s going on is to use the vssadmin tool from an elevated command prompt.VSSADMIN? I was expecting a GUI like the one in Windows XP, but if this is aimed at IT Pros, a console-mode administration tool makes perfect sense. The blog post doesn’t explain how to get an elevated command prompt on Windows Vista. The quickest way to do it is to type “CMD” into the “start search” box you get after clicking on the “start” icon at the bottom left of your screen. Then press the key combination Ctrl-Shift-Enter, and finally agree that you want to do this. The console window will open marked as “Administrator.” An alternate way is to navigate to the Command Prompt entry under All Programs/Accessories, right click, and choose “Run as Administrator.” You’ll still get the UAC prompt, and wind up with the same elevated console window. The command to find out how much space is being used on your volumes for restore points and other shadow storage is >vssadmin list shadowstorage The command to change the storage allocation is >vssadmin resize shadowstorage /on=<vol> /for=<vol> /MaxSize=<size> You can get more information from the Technet blog entry, and from running the vssadmin tool without any arguments.I have heard that there were Vista beta testers who saw 1 GB restore point sizes because of the large shadow copies on disks with many changes. If that’s the case, then 15% of the volume really is a reasonable allocation of space. Software Development