Be wary of Shadow Copy limitations

One of the nice things about Shadow Copy is that it doesn't carry much of a performance penalty while the Shadow Copies are being made. "Not much", it's worth noting, is not the same as none. In a heavily-loaded server, it is worthwhile to set aside a disk for Shadow Copies, in order to eliminate extra head seeks.

However, Microsoft cautions there are limits to the way Shadow Copy is used. Shadow Copy isn't intended as a complete backup solution for shared folders. For example, while Shadow Copy does make copies of DLLs (Dynamic Link Libraries), it is not recommended to use those copies to recover DLLs in case of emergency.

Microsoft also warns against using a Shadow Copy to back up disk image. Although Shadow Copy will recursively recover all the files in a volume, it doesn't delete files. That means it doesn't restore the disk as it was at the time the Shadow Copy was made. It is also slow for large quantities of data. Microsoft suggests restoring the image from backup media instead.

Microsoft has a FAQ on using Shadow Copies of shared folders at:
www.microsoft.com/windowsserver2003/techinfo/overview/scrfaq.mspx.

For more information:

Tip: Eight guidelines to Windows-based snapshots

Tip: Resource guide to snapshots (or point-in-time copies)