The hidden treasures of Sysinternals
Every few months I make a pilgrimage to the Sysinternals website to look at its superb collection of tools. It’s now hosted inside the Microsoft Technet monster since its authors joined Microsoft as employees some while ago, but the value of their site is still as strong as ever and the tools are now guaranteed not to be ignored or left to rust.
So what’s new there? Well, there’s a tool called Disk2vhd, which creates VHDs (virtual hard disks, Microsoft’s VM disk format) from physical drives. You can then use these within Virtual PC or the server-side Hyper-V engine. What’s important about Disk2vhd is that you can even run it on a disk that’s actually in use at the time, which is like pulling yourself up by your own boot laces.
It can do this because it uses the Windows Volume Snapshot technology to take an instant snapshot of the disk on which to do its work, even while the disk continues to be written and read by other programs.
You can even run Disk2vhd on a disk that’s actually in use at the time, which is like pulling yourself up by your own boot laces
A couple of points to note here. Obviously, when you take a virtualised snapshot for the first time within your chosen VM environment, it won’t be running on the original native hardware. Fortunately, Windows does a plug-and-play hunt for new drivers, and should have no problem swapping out the original hardware-specific drivers for the correct ones for the VM environment.
A second gotcha is worth quoting from the site: “Note: do not attach to VHDs on the same system on which you created them if you plan on booting from them. If you do so, Windows will assign the VHD a new disk signature to avoid a collision with the signature of the VHD’s source disk. Windows references disks in the boot configuration database (BCD) by disk signature, so when that happens Windows booted in a VM will fail to locate the boot disk.”
Which should be a salutary reminder that Windows will happily rewrite these signatures for you, but might screw things up in the process.
There’s another Sysinternals tool I’ve used recently called DiskMon, which captures information about every read and write to your hard disk and shows it in a fast-moving list. The reason I needed this tool was that a Windows Vista machine had suddenly started thrashing its disk for no apparent reason.
Task Manager didn’t really show me what was happening and I’d already turned off the Windows Search service, which is the built-in disk indexer engine within Vista. DiskMon wouldn’t run on Vista at first, just returning an error – it turned out I needed to run it as an Administrator to give it elevated privileges. Once I’d done this it was soon obvious which application was chewing away at the disk, and a quick exorcism resulted. It’s times like this when a highly focused tool can help you get to the answer quickly.
Another useful present from Microsoft (it must be Christmas) is a tool that lets you blow ISO images onto any bootable medium such as a USB stick. This permits you to take an ISO image of, for example, Windows 7 and write it to a suitably large USB stick, which you’ll need to do if you want to install it onto a laptop or netbook that has no local CD/DVD drive.