Yesterday, MS honcho Steven Sinofsky posted an entry to the Building Windows 8 blog entitled “Accessing data in ISO and VHD files.” It explains how, in Sinofsky’s own words “Windows 8 enables easy access to the contents of two important storage formats: ISO and VHD files.”
ISO is, of course, an archive file format that represents a disk image of an optical disk or other storage medium, and usually takes .iso as its file extension. Microsoft uses ISO images to package up downloads of its various OSes and other products but until Windows 8, you’ve had to grab some kind of 3rd party ISO handling program to unpack them in a readable on-disk format. I use Alex Feinman’s excellent ISO Recorder v3.1, which functions as a Windows Explorer shell extension, but there are lots of great tools to do this job on earlier Windows versions.
VHD is a Microsoft virtual hard disk format (originally created by Connectix, since acquired by MS, for the Microsoft Virtual PC–and later Virtual Server and Hyper-V–products). It represents an image of what might appear on a physical hard disk drive, including disk partitions, a file system, files, folders, and so forth. A VHD represents the storage space for a virtual machine in the form of a single portmanteau file that takes the extension .vhd. Microsoft makes the VHD Image Format Specification freely available to third parties under its Open Specification Promise, which “provides broad use of Microsoft patented technology necessary to implement a list of covered specifications…[whose] goal…is to provide our customers and partners with additional options for implementing interoperable solutions.”
What does this all mean? It means you’ll be able to mount and read ISOs and VHDs from inside Windows Explorer in Windows 8, without having to install additional software. Unfortunately, it looks like the planned ISO implementation will be read-only, though. If you want to create ISOs, you’ll still have to install additional software on Windows 8. The same restrictions do not apply to VHDs, though: of them, Sinofsky says “you can…work with the virtual hard disk just like any other file storage in your system, whether you are modifying, adding, or removing files.”
Sounds good! When can we start playing with this new technology?