How to read and write a virtual hard disk when it is opened by another application

Question

How to read and write a "virtual hard disk" when it is opened by "another application"?

virtual hard disk - referring to hard disk that are created by a virtualization application (e.g. Virtual PC, Virtual Box, VMware Player)

another application - referring to virtualization application (e.g. Virtual PC, Virtual Box, VMware Player)

Answer 1

This would seem to be a staggeringly bad idea. Imagine if something in your computer started fiddling with the data on your disk as you were using it - things would end very poorly. And that's what you're asking here - the virtual machine is in operation, presumably, and you'd like to do something to its disk while it's in use. You'd be pulling the rug out from under the virtualized OS.

Read-only access, even, has many pitfalls - you'd need to assume that the data will be inconsistent, as the writes take time and are often spread out between sectors. If you read a sector as it's being written, it'll be useless data.

This is a tricky, but useful, thing to do if the VM isn't running. But it is, so can you communicate with it over the network? All three products you list have special host-to-guest file I/O capabilities that allow the guest to access files on the host, and vice-versa. Let the guest OS get or write your data.