mabb

I've found the page buried in the Defraggler documentation that goes some way to explaining this, but it's not strictly correct: Windows Vista and volume shadow copies The Microsoft link (as given by an earlier poster above) is more helpful: Microsoft Support: Shadow copies may be lost when you defragment a volume The Defraggler documentation says the problem is with third-party defragmentation tools, but it occurs with Windows built-in one too, as explained in the Microsoft Support page. In this page: Problems running Defraggler the Defraggler documentation says Windows Vista creates an automatic System Restore point when you run Defraggler, but it isn't true. The Microsoft Support page explains what really happens, which is that the System Shadow Copy provider keeps track of all file write events at a 16KB block level, so it grows the Shadow Copy information stored in the System Volume Information file, and it can grow so large that some or all System Restore points have to be removed, to respect the user's chosen limit on disk space for System Restore.

The thing is, if it was a major defrag you did that time with Defraggler, the System Volume Information will have tried to grow to bigger than the 10GB limit you have set. This can easily happen. Then you do lose all System Restore Points. It's a problem with Windows 7 and Vista, as explained in the Microsoft Support page, and it would have occurred with Windows built-in Disk Defragmenter too, or indeed any defragmenter. It all depends whether the size of the SVI for all that file moving of small fragments is greater than your limit setting. Either increase the System Restore limit when you do a major defrag, or you have to accept losing all System Restore Points. In this, it makes essentially no difference what defrag program you use - there could be marginal differences in the number of file moves to complete the defrag, but it is unlikely to make any difference. I suspect Defraggler is pretty efficient anyway. The main strength of Defraggler is the ability to do a Quick Defrag on just the files with small fragments, or defrag just selected files. There is actually little point moving around big chunks of large files in a full defrag, so that is the advantage over Windows built-in Disk Defragmenter. It saves a lot of time and disk bashing! Unless your disk is getting full, there is probably no particular reason to set a low limit for System Restore.

Interesting. However, I tested with Windows 7 Disk Defragmenter, and my SVI rose from 26.8GB to 29.78GB as reported by System Restore. It's interesting that you had used 98% of your max size setting for SVI before the Defrag. Can you be certain you didn't lose the oldest System Restore point? The very fact the size of the SVI changed suggests this. If the SVI was unaffected, it would have been 9.8GB before and after. Nothing about a defrag should reduce the SVI, except by removing a System Restore Point, which happens automatically every time the limit is reached. The way to test it reliably would be to increase the limit setting so there is plenty of space for the SVI to grow. If the SVI had stayed the same size, I would have asked whether your disk has cluster sizes of 16KB or greater. Have you read the Microsoft Support page linked to above? (I know it's written before Windows 7, but I'm sure it still applies, as the Shadow Copy service is still the same).

Windows' System Volume Information file distorts Defraggler's fragmentation percentage because the size of the SVI grows during defragmentation and the SVI remains fragmented. This can make it look like Defraggler is actually increasing fragmentation. Windows' built-in defragmenter ignores the SVI in its figures. Fragmentation of the SVI is irrelevant to Windows' performance, so it is fair to ingnore it. It would be helpful to show the SVI in a different colour on Defraggler's drive map, to show the true fragmentation situation for ordinary files. The SVI is not really a file in the ordinary sense, as it contains information about changes in all other files on the disk.

The problem with Windows 7 and Vista increasing the size of the System Volume Information file (containing the Volume Shadow Copy for System Restore) also occurs with Windows' own built-in Disk Defragmenter - it is not caused by Defraggler. The Microsoft link given above is very helpful in explaining this. If it is an issue, the only real solution is to begin with the disk volume formated with a cluster size of 16KB or larger for volumes on which System Restore will be enabled, though pretty much all PCs will be set up with a smaller cluster size by the manufacturer! It needs to be flagged as a known issue in the FAQ with an explanation. Switching off System Restore should be a last resort because it is a valuable part of Windows' protection. However, defragmenting a large volume of files at once, especially if the disk is nearly full, will cause System Restore to fail anyway for lack of space. If a disk is filling up with files gradually, regularly defragmenting avoids the problem of a massive surge in System Volume Information.