Dario IT Solutions Blog

In order to boot a Hyper-V child partition (guest) from an iSCSI LUN you need to expose that LUN to the parent partition (host), make sure the LUN is set as an offline disk in the host and then use the Passthrough option to expose the disk to the guest as IDE (ATA).

With that, you can successfully boot a Hyper-V guest from an iSCSI LUN. In fact, that works just the same for a fibre-channel LUN or SAS disks.

Here’s what the configuration of that virtual disk would look like:

There are also third-party solutions that will that will allow a Hyper-V guest to boot from an iSCSI LUN exposed directly to the guest. You can check a product from EmBoot that does exactly that at http://www.emboot.com.

How about a picture?

In the picture you see the different ways to expose a disk to a Hyper-V parent partition (host) and child partition (guest):

• C: = Using a VHD file on a directly attached disk (X:) on the host
• D: = Using passthrough to a directly attached disk on the host
• E: = Using a VHD file on a SAN LUN mounted as a volume (Y:) on the host
• F: = Using passthrough to a SAN LUN exposed to the host
• G: = Using an iSCSI LUN exposed directly to the guest

Note that, for the first four options, the disk can be exposed to the guest as either SCSI or IDE (ATA), regardless of the physical disk interface used on the host. Also note that the last option is only available for iSCSI SANs, not fibre-channel.

For all the details of what you can and cannot do in each scenario, check this post:
http://blogs.microsoft.co.il/blogs/dario/archive/2008/08/26/windows-server-2008-hyper-v-storage.aspx

Related posts:

1. Windows Server 2008 Hyper-V Storage
2. Hyper-V Deployment – Notes from the field
3. Hyper-V : Notes and Guidelines from the field
4. Hyper-V Failover Clustering Using Normal Shares
5. Microsoft iSCSI Software Initiator Version 2.07 (build 3640)