I am disappointed to say that Toucan will not use the Volume Snapshot Service in a future version. The idea behind VSS is that it allows you to copy files which are in use, for example an Outlook .pst file whilst Outlook is open. As there were a number of requests for this feature, and indeed I too thought it would be useful I have had it on the todo list for a while, and indeed I intended to have it added for version 2.1.3 which is now in pre-release here.
Unfortunately however after looking through the VSS SDK and at a number of posts on forums around the internet I have realised it is not as straight forward as I hope to add support to Toucan, a fairly large amount of code would need to be rewritten.
The reason for this is that Toucan uses the wxWidgets library instead of platform specific calls, for example instead of calling the Win32 function CopyFile Toucan calls wxCopyFile which, depending on the platform it is being compiled for ends up as the native file copy call. VSS however requires you to take a snapshot of an entire volume (for example C: or D:) and it then returns a special path to the shdow copy, for example
\\?\GLOBALROOT\Device\HarddiskVolumeShadowCopy1. The way Toucan (and I believe wxWidgets) works means it requires filenames such as
C:\test throughout the codebase (this is also the reason that support for UNC paths has not been added). To support this change of filename type would require a substantial amount of time, that I would prefer to devote to other Toucan todo's, which I hope to post about soon!
Thanks for your understanding
P.S. For more info on VSS see this blog post by Craig Andera.