Jump to content
RESET Forums (homeservershow.com)

Virtualization Question


pcdoc
 Share

Recommended Posts

I am about to go down this road but have a question. It seems to me from the different things I have read that you have to do a fresh install everytime. Is there a way to attach directly to an installed hard drive?

Link to comment
Share on other sites

Hey pcdoc, there is a way to do this, however I wouldn't recommend it due to its possible challenges. When you install an OS, it customizes the install and associated drivers based on the hardware it detects during the install. So on your physical install it detects your CPU, ram, chipset, etc. that is there. If you were to take that same HDD with the native OS installed, and add connect it to virtual hardware the OS is going to start up and begin to freak out because the new CPU doesn't match the one it thought was there, the new ram doesn't match the old RAM it thought was there, etc.

Older OS's handle this much worse than new OS's do. It's the same thing as taking an old XP install from 1 set of hardware and trying to boot it off another set of hardware, bad things usually happen. Another thing to consider is that newer OS's have adaptations they make when they detect they're being installed in a virtual machine which would be to your benefit so they perform better. If you're moving an OS that was installed in a physical system before you'd be missing out on those optimizations.

Yes you can do this with Hyper-V, create a new VM, don't assign it any VHD, then pass-through the SATA disk that has your OS already installed on it, and it "should" work if the OS has native support for the virtual hardware your VM is passing it. If it doesn't, you'll be looking at some nice BSOD's.

Link to comment
Share on other sites

THanks wodysweb. Your analogy is understood. Having only tried Hyper V once, I understand not assigning a VHD but do not follow your pass-through suggestion, can you expain. Thanks for insight and the great write up.

Link to comment
Share on other sites

Basically, instead of assigning a VHD at this stage http://homeservershow.com/wp-content/uploads/2010/02/Untitled9.png you would select the bottom radio button to attach a hard disk later. Then, once your VM has been created you have the option in Hyper-V to "pass" a SATA hard drive directly to the VM, instead of having the hard drive connected via Hyper-V. Instead of the normal communication path of [ virtual machine - Hyper-V - VHD - SATA disk] it would be [virtual machine - direct to SATA disk], bypassing the need for a VHD and using the whole disk.

The view to the virtual machine would be the same, because a VHD file is presented to the virtual machine as if it really is a disk, when in reality it is a file sitting somewhere. By passing through the disk, you would allow the VM to view your already existing hard drive with your already installed OS, and if the stars align the OS would boot and not throw any errors due to driver/device errors.

The option to "pass through" is not an available feature in ESX or ESXi natively. Hope that rambling makes some sense...

Link to comment
Share on other sites

Guest no-control

Damn that would have been nice to know when I was fooling around with my previous VM build. Still debating the VM WHS vs dedicated H/W.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...