Storing VM on a USB drive?

P

PrinceZordar

Member
I tried creating a VM on a USB hard drive for Windows XP. I have one on Boot Camp which works fine (for the most part) but I needed one that could be joined to a Windows domain. XP installed fine, joined the domain, no problems, downloaded a ton of updates, now it won't boot. Says NTFS.SYS is missing.

I have also tried installing Vista Ultimate and Business on the same USB drive. Every time, it gets to Expanding files and then says it couldn't continue. The error code given seems to point to corrupt installation media, but I have tried three DVD's and an ISO image downloaded from Microsoft's Volume Licensing site. Same error every time.

Is there an issue with installing to a USB drive that just gacks the VM? I've been using the USB drive for external storage for several months, and have had no other issues with it.

-Z
 
This is a possible scenario that would explain the problem. First, though, understand that either OS X or Windows can access the USB drive, but both cannot do so at the same time. So...

OS X has the USB drive mounted and Parallels is started and is commanded to load and run a Windows virtual machine found on the USB drive. All well and good because Parallels is an OS X application and OS X has the USB drive mounted. Then Windows starts up and needs access to its boot disk, a virtual disk stored on the Mac attached USB drive. Windows doesn't know it's running in a virtual machine and just needs to access that USB disk but OS X has it mounted and recalling that both operating systems cannot use the USB disk at the same time, Windows loses. This is called device contention.
 
Crud. I did not consider that as an issue, but now that you point it out it makes perfect sense. I'm surprised it worked as long as it did.

Back to the drawing board... thanks for the reply.

-Z
 
dkp said:
This is a possible scenario that would explain the problem. First, though, understand that either OS X or Windows can access the USB drive, but both cannot do so at the same time. So...

OS X has the USB drive mounted and Parallels is started and is commanded to load and run a Windows virtual machine found on the USB drive. All well and good because Parallels is an OS X application and OS X has the USB drive mounted. Then Windows starts up and needs access to its boot disk, a virtual disk stored on the Mac attached USB drive. Windows doesn't know it's running in a virtual machine and just needs to access that USB disk but OS X has it mounted and recalling that both operating systems cannot use the USB disk at the same time, Windows loses. This is called device contention.
Click to expand...

This is strange (unless its boot camp on the usb drive which makes sense why it won't work)

But if its a virtual hard drive on the USB drive, it should work fine.. as parallels should point to the virtual C: drive which is a file not a drive in os x.
 
Boot Camp is on the internal hard disk and works fine (more or less.)

The VMs I was trying to create were both on an external USB HD. I managed to get XP Pro installed and running; it didn't crash until I tried to download updates. The Vista install, now I can see why that failed - Mac OS X was running Parallels, which had access to the VM on the USB drive. I guess the handoff from OS X to Vista wasn't as graceful as it could have been, thus Vista barfed all over itself.

I have since installed Vista to the internal HD as a VM, and it ran just fine.

-Z
 
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