Hyper-V: How to get the most from your virtualized disk performance

re: Hyper-V: How to get the most from your virtualized disk performance

Rob McShinsky — Sun, 16 Dec 2007 22:22:08 GMT

"You can not boot from a SCSI controller. This means an IDE disk will be required."

So I have to boot from an virtual IDE drive meaning the OS has to be on the virtual IDE drive? That can't be right can it?

Rob

No boot from IDE

tvoellm — Mon, 17 Dec 2007 21:22:16 GMT

Yes it is true you can not boot from SCSI. Our virtual BIOS does not support this today. It does support (always subject to change because this software is not RTM);

IDE

Legacy Network Adapter

Floppy

The root reason is SCSI in a synthetic device and there is no VMBUS until after boot.

Tony

re: Hyper-V: How to get the most from your virtualized disk performance

Anthony — Mon, 31 Dec 2007 18:52:02 GMT

You could support booting directly from the PV SCSI disk with something like extboot. See http://blog.codemonkey.ws/2007/12/first-release-of-extboot.html

re: Hyper-V: How to get the most from your virtualized disk performance

Mike — Tue, 01 Jan 2008 04:18:33 GMT

Will the Scsi-boot be supported in RTM?

re: Hyper-V: How to get the most from your virtualized disk performance

Kofler — Mon, 07 Jan 2008 17:00:15 GMT

And what about "seamless" Virtual Server to Hyper-V conversation. Only a marketing bluff?

re: Hyper-V: How to get the most from your virtualized disk performance

Roberto — Mon, 10 Mar 2008 19:39:00 GMT

Anthony,

As a former developer, I found the Hyper-V architecture really fantastic: it's elegant, intelligent e promising. From the developer point of view, you guys have done an excellent job (that has room for improvements, of course). Things like the virtual switch were really smart ideas.

But, from the infrastructure point of view, things like "won't boot from SCSI disks" are inadmissible. Statements like these (about the SCSI boot) can just rise another statement: "You gotta be kidding".

In a product built for Datacenters, there's no such thing as "won't boot from SCSI disk". Even saying that Windows Server 2008 is not exclusively for Datacenters, we can fool ourselves thinking that it THERE (the Datacenters) where it will be deployed most times - it's an obvius move. If you (a "generic" you) want to compete with VMWare and Virtual Iron, this kind of problem HAS TO disappear. It IS a showstopper. Many people excited about Hyper-V (including me) WILL NOT use it in their Datacenters with this kind of bug or problem or "collateral effect". There is no way to convince IT staff to add an IDE disk to a virtual machine just to boot - or worse: to move the OS to an IDE disk to do that. There is simply NO chance, and I'm not speaking only for myself...

Come on - you guys are doing an excellent job, and you (the team) can surelly find some clever solution for this. The SCSI driver could run emulated until the VMBus can be loaded, or the BIOS could do the boot part until the VMBus is up - I don't know how, but one thing is pretty sure in the corporate market for Hyper-V: you guys will HAVE to find a way..

Thanks,

Roberto P.R.

re: Hyper-V: How to get the most from your virtualized disk performance

Kyle — Wed, 23 Apr 2008 16:42:21 GMT

This really irritates me as well. I wanted to migrate from VMWare Server to Hyper-V, now I am not sure I can/will. Repair installs on an existing server just don't make sense. There should be a way to support "legacy" SCSI drives at the very least.

Device Access in Hyper-V

Virtualization Blogs — Sun, 11 May 2008 13:05:15 GMT

Ok. This is what I've learned so far about device access in Hyper-V. For device access in Hyper-V

re: Hyper-V: How to get the most from your virtualized disk performance

mescwb — Sun, 18 May 2008 06:44:49 GMT

Does a VHD created attached to a virtual scsi can be mounted in a virtual ide?

[[Tony's Reply]]

Let me try and parse this. Are you asking if a VHD attached to a VM on the Virtual SCSI actually reside on an IDE disk? If so the answer is yes. VHD's can also reside in LUNs, ... The actual disk / LUN can be different from the virtual controller.

re: Hyper-V: How to get the most from your virtualized disk performance

Jimmy — Mon, 02 Jun 2008 05:18:35 GMT

What he's actually asking is if a VHD is attached to a SCSI virtual controller, can it be attached to an IDE virtual controller later?

[Tony's Reply] VHD's have no knowledge of the virtual interface you connect them to. You can attach SCSI now and IDE later.

SCSI performance using Fibre channel on host not good

Kevin — Thu, 12 Feb 2009 21:04:22 GMT

Hi,

I have an issue that we are using IBM Storage Manager v10 on the 2008 host and find that the virtual SCSI driver within Hyper-V to be worse performance then IDE driver as a data drive. our fibre channel is using MPIO windows x64 driver on the host connecting to a DS4300 hwne using the SCSI driver we were getting 10 MB/s performance, (single drive RAID 1 array) on the IDE driver we are getting 40 Mb/sec (which is closer to the real performance

any ideas ?

----

Tony's reply - What type of disk are you using the IDE and SCSI? Fixed / Diff / VHD? Is this WS08 Hyper-V or WS08R2?

re: Hyper-V: How to get the most from your virtualized disk performance

Carl — Fri, 15 May 2009 16:34:38 GMT

Has the "no booting from SCSI in Hyper-V" been fixed yet?

[Tony's Reply] In Windows Server 2008 R2 we only support booting from Virtual IDE. In my experience having the OS on virtual IDE has had little overall impact on performance. I do recommend putting data on virtual SCSI drives.

Is there something specific you have measured or seen?