virtualbox.org

I'm running VirtualBox on Win 7 and have several Linux guest OSes as VMs sharing directories between the host and guests. Up 'til now that's been running fine. Just now I ran a Linux application, mkisofs, that creates an ISO image file of a directory and directed the output to a shared directory on the Windows host. Big mistake! Most of the destination directory was wiped out. Fortunately Windows itself still runs and I don't think I've lost anything else.

So... This is a warning to other users to only use cp to copy files into a host directory, and a query to the Vbox team to ask what the heck is happening here.

What does "sharing directories between the host and guests" mean?

If that means network shared folders then I do not see how it could possibly behave as you describe: a network shared folder is simply an application running on the server PC which responds to network requests to read and write data from files. It does nothing unsual for any application that reads and writes files, and in particular it isn't possible for it to cause disk corruption - the worst that can happen is you run out of disk space or bugs might very occasionally cause a problem with files actually being written.

If, however, "sharing directories" actually means raw disk access, then corruption would certainly be the result if you write to a shared drive, and since you ignored all the warnings you would totally deserve every bad thing that happens. Evolution in action.