Booting Hyper-V VMs off of iSCSI?

Booting Hyper-V VMs off of iSCSI?

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Recently there has been some confusion over whether it will be possible to boot Hyper-V virtual machines off of iSCSI.  I would like to clear this up with a strong statement of "No, but yes!"

:-)

Okay - now for the longer answer.

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:

  1. Attach the iSCSI LUN to the parent partition.
  2. Create a new virtual machine and opt to configure the hard disk later.
  3. Open the settings for the new virtual machine and select the first IDE controller.
  4. Select to add a disk drive.
  5. On the disk drive configuration page select to use a physical hard disk, and select the iSCSI LUN.
  6. 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.

Cheers,
Ben

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  • There's one more way to do this - and it does not require exposing iSCSI via the parent partition. You can access iSCSI via a software initiator when booting from the VM's NIC using PXE....it can then chain and bootstrap 2003 / Vista / 2008 etc. using the Microsoft software iSCSI initiator within the guest VM.

    Better yet, you can boot a diskless 2008 Server Core with Hyper-V from iSCSI, and then its guest VMs themselves can also boot from iSCSI without having to define any additional LUNs on Server Core.

    Steve Marfisi

    emBoot Inc.

  • My original post at http://blogs.technet.com/josebda/archive/2008/02/14/storage-options-for-windows-server-2008-s-hyper-v.aspx was misinterpreted. I said that Hyper-V does not have a *native* option to boot from from the iSCSI LUN exposed *directly* to the guest (not exposed to the host). I did mention that you can boot from a passthrough LUN (iSCSI or FC).

    To clear any misunderstanding, I have added a second post at http://blogs.technet.com/josebda/archive/2008/03/05/more-on-storage-options-for-windows-server-2008-s-hyper-v.aspx, making that detail absolutely clear and showing some pictures to help further differentiate the two scenarios.

    As Steve from emBoot mentioned, you can also use a thirdy-party solution that starts with a PXE boot and then chains to iSCSI.

  • Hi, I've been using Virtual Server for a while, and have recently been experimenting with iSCSI.  I have my VM's on the attached iSCSI LUN.  These work fine, but when rebooting the server the iSCSI Initiator hasn't completed the drive setup before the Virtual Server service starts.  I have the same issue with SQL2005 with databases on the iSCSI LUN.  I have tried using "dependancies" on the services, but this still doesn't seem to solve the problem.  I've resorted to using starting the services with a delayed script through the scheduler's "on boot" schedule.  Do you know of a better way to ensure that the iSCSI Initiator has completed successfully before other dependent services start.  I've noticed that 2008 now has a "delayed start" option for services.

    Shame there isn't iSCSI boot emulation on the Virtual Server NICs for testing.

    Thanks, Richard.

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