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

Posted by Alessandro Perilli   |   Thursday, February 07, 2008   |   2 Comments

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...

2 Comments

Anonymous Steve Marfisi / emBoot Wednesday, February 13, 2008 10:04:00 PM  
Contrary to Jose's Barreto's blog, Hyper-V does indeed support iSCSI boot, both for the hypervisor-on-2008 and for its guest VMs. We've tested both successfully.

For our tests on guest VMs, we first added a legacy NIC (DEC 21140). We then installed our winBoot/i software as per our normal procedure, copied the VM's contents up to an iSCSI lun, set the BIOS to boot from network and it worked.

Booting a Hyper-V-on-2008 was a bit trickier - the Hyper-V installation adds bindings to an existing NIC that can get in the way of iSCSI boot. As per our past experience with this on Virtual Server 2005 R2 (see http://65.93.237.220/forum/forums/thread-view.asp?tid=203&posts=1)
the trick is to use a 2nd NIC bound to Hyper-V and then set the boot NIC unbound from Hyper-V. We then installed our winBoot/i v2.5 beta client on this, SystemCopy up to iSCSI SAN, and booted successfully from iSCSI with VMs still working under Hyper-V.

Screenshots and documentation details will be added to our website support forums within a few days.

Steve Marfisi
emBoot Inc.
Anonymous Steve Marfisi Wednesday, February 13, 2008 10:20:00 PM  
Contrary to Jose's Barreto's blog, Hyper-V does indeed support iSCSI boot, both for the hypervisor-on-2008 and for its guest VMs. We've tested both successfully.

For our tests on guest VMs, we first added a legacy NIC (DEC 21140). We then installed our winBoot/i software as per our normal procedure, copied the VM's contents up to an iSCSI lun, set the BIOS to boot from network and it worked.

Booting a Hyper-V-on-2008 was a bit trickier - the Hyper-V installation adds bindings to an existing NIC that can get in the way of iSCSI boot. As per our past experience with this on Virtual Server 2005 R2 (see http://65.93.237.220/forum/forums/thread-view.asp?tid=203&posts=1)
the trick is to use a 2nd NIC bound to Hyper-V and then set the boot NIC unbound from Hyper-V. We then installed our winBoot/i v2.5 beta client on this, SystemCopy up to iSCSI SAN, and booted successfully from iSCSI with VMs still working under Hyper-V.

Screenshots and documentation details will be added to our website support forums within a few days.

Steve Marfisi
emBoot Inc.

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