Windows 2012 R2, Storage Server, iSCSI, VHDX, Hyper-V Cluster.

Hey Guys

I recently setup a new storage server (WIndows 2012 R2, iSCSI and 2x Hyper-V Hosts. I have a question about "VHDX Drives" presented to a VM host, and then creating a VM (which uses vhdx) onto the presented "VHDX drive". I put this post on technet but no luck. (Bottom of page) - that is nested VHDX's.

So here is what I have created:

1) Several LUNs created as "Diskname.vhdx"
2) Those LUNs are then presented to both my VMhosts
3) I created a Hyper-V Failover Cluster (2 VM hosts)
4) Then I presented my newly provisioned LUNs out and started setting up VMs.

Here is my question though, since an iSCSI "Drive" is basically just a VHDX file, and since VMs are basically stored on VHDX files.
Am I not creating a VHDX within a VHDX? Is that right way to do this? I realize my question may sound stupid, but in the past I simply created a VHD file on standard HDD. Now I am basically nesting vhdx's. ?

Thanks,
Robert

here is the technet link: https://social.technet.microsoft.com/Forums/windowsserver/en-US/cd5be36f-3683-48aa-9361-40dc7480ef31/windows-2012-r2-hyperv-shared-csv-iscsi-and-sata?forum=winserverClustering#fde82eee-5cd3-4c8a-bf3a-52f56a1a3de3

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LVL 64

Cliff GaliherCommented: 2016-09-27

Yes, that is exactly what you are doing, and yes that is the right way to do it. The VHDX format was designed and envisioned with this as one of the use cases and results, and is very efficient at nesting, unlike the old VHD format. No worries. Onward.

LVL 6

castellansolutionsAuthor Commented: 2016-09-27

ok so its ok to do it with VHDX files, but not with VHD files? And, is there a way to get Windows 2012R2 to "Present" the Storage without it creating an iSCSI VHDX file? Similar to real SAN which would not present a VHDX ?

Thanks,

Robert

It is "okay" to do it with vhd files as well, but is not very efficient and there is a performance hit. VHDX doesn't have those significant hurdles.

And no, the iSCSI target in windows relies on storage virtualization. Although to be accurate, the VHDX isn't "presented" at all. A logical drive is presented to the iSCSI initiator. The initiator doesn't know or care that the underlying storage is a VHDX file. That is self contained on the iSCSI target. And "real" SANs use similar tricks, albeit not with the VHDX format specifically. But if you dig into a SAN, most run a variant of links and aggregate their storage with a proprietary file format. Similar in function to VHDX. Don't get hung up just because windows lets you peak behind the curtain more than brand X's black box.

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Thanks Cliff. I am just having a hard time wrapping head around the "VHDX inside a VHDX". I have used virtualization for many years, but only on a small scale. 2 or VM hosts with 5 or 6 VMs on each. Now i am doing it the right way.

Thanks for the confirmation.

Robert

Windows 2012 R2, Storage Server, iSCSI, VHDX, Hyper-V Cluster.

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