Question:

on a VM, is it possible to have simultaneously 2 CDROM, 2 Floppy drives, real or virtual?

I have been told that is not possible under virtual PC 2004, but what about VS?

Answer:

You can programmatically attach multiple virtual DVD ROM drives on IDE or SCSI bus. The virtual DVD ROM drives can be tied to physical drives or ISO files.

You cannot programmatically attach a second virtual floppy drive. The virtual floppy drive can be tied to physical drive letter or VFD file.

Reply:

thank you.

I was hoping I can attach ISO via ini/vmc files or without programming..

Too bad

BTW: what happens if an vm is restored from an image of an physical PC with 2 floppy and multiple CD/DVD drives?

What if the host supports two floppy drives and 1 DVD and CD drive?

My Reply:

Actually, I do not see why you hope to be able to attach ISO via INI/VMC files and see that as "not programming"... because modifying INI/VMC files require "programming" to do the search/modification, no matter the tool that you use. And between that choice and a commandline tool that can use the Virtual Server Administration API to manipulate VirtualMachine state, I see modification of INI/VMC file to be a fragile, *nix "parse and pray" sort of approach. Sorry... but I do not miss it one bit. ;-)

Regarding your interesting questions about what happens when the host supports hardware type or quantity not matched by VirtualMachine or if software image taken from a machine with different specifications than the VirtualMachine is restored...

No one said that VirtualMachine represents all possible PC hardware combinations. In fact, according to documentation, Virtual Server emulates very specific types of hardware... for the purposes of running software, not to emulate arbitrary hardware.. For example:

  • When the Host has the latest ATI video card that supports TV Tuner, advanced 3D graphics, etc - the GuestOS in the VirtualMachine only sees a S3 Video card with no TV Tuner, no advanced 3D graphics, etc.
  • When the Host has a CDROM drive - the GuestOS still sees a virtual DVD drive and you can attach a real DVD ISO, but you obviously cannot connect the physical CDROM drive to the virtual DVD and then make the physical CDROM drive read a DVD disc even if the GuestOS thinks it is a virtual DVD drive. The GuestOS's virtual DVD drive behaves like the attached physical CDROM drive.

    In short, your virtual DVD drive performs like the physical CDROM drive; only difference is that the GuestOS thinks it is a DVD drive when it is not. This is no big deal. Consider that GuestOS thinks its network card is always 100MBit even if the physical one is 10MBit or 1000MBit, but you still get the actual performance of the physical hardware.

So, it does not matter if the host supports two floppy drives. The VirtualMachine only has one - just like the Host supports video with advanced 3D graphics but the VirtualMachine does not. Host can have features not available in the Guest.

And if the host has a CDROM and DVD drive, the Virtual Machine can be configured to see two virtual DVD drives, but one performs like a CDROM and the other the DVD. This is no big deal because we already know that Virtual Server emulates specific hardware types for the purposes of running software. In other words, this arrangement fails for the case where the intent is to detect a virtual CDROM drive, not a virtual DVD drive performing like a CDROM, but I hope you agree that this scenario is basically contrived and unsupported.

Likewise, the restoration of an image of a physical PC with two floppies is also not interesting. You are restoring a software image into a VirtualMachine of a given configuration that is different than the original. This is no different than if you imaged on one PC and then restored it to a completely different PC. Once again, Virtual Server is not in the business to emulate arbitrary hardware for detection, so this is OK.

//David