Hyper-V doesn’t support iSCSI boot for virtual machines

From his corporate blog Jose Barreto, System Architect at Microsoft, details all the storage options that will be available with upcoming Hyper-V: DAS (SAS, SATA), Fibre Channel and iSCSI. Unfortunately:

…Hyper-V’s virtual BIOS does not support booting to iSCSI directly, so you will still need to have at least one disk available to the guest as an IDE disk so you can boot to it…

Barreto’s post includes some valuable matrix to compare virtual machines limitations for each scenario and it’s a recommended reading.

All the storage options should be already available in the current beta 1, included in the just released Windows Server 2008 RTM.

Update: Ben Armstrong, Program Manager on Core Virtualization at Microsoft, provides additional details about the Hyper-V iSCSI capabilities and reveals that the goal can be accomplished in a way:

Hyper-V virtual machines do not emulate an iSCSI HBA or allow you to pass a physical iSCSI HBA through to the virtual machine. However, as Hyper-V supports booting virtual machines directly off of physical hard disks, you can attach an iSCSI LUN to the parent partition and then boot the virtual machine off of it.

In order to do this you would need to:

  • Attach the iSCSI LUN to the parent partition.
  • Create a new virtual machine and opt to configure the hard disk later.
  • Open the settings for the new virtual machine and select the first IDE controller.
  • Select to add a disk drive.
  • On the disk drive configuration page select to use a physical hard disk, and select the iSCSI LUN.
  • Apply changes and close the virtual machine settings.

Now you can boot the virtual machine directly off the iSCSI LUN by just starting it up…