Hyper-V will not boot virtual SCSI devices

Posted by virtualization.info Staff   |   Monday, December 31st, 2007   |  

An unexpected bad news closes the year: from its corporate blog Anthony F. Voellm, Principal Software Development Lead of Hyper-V at Microsoft, reveals that the upcoming hypervisor will not boot from virtual SCSI hard drives.

There are two types of disk controllers that Hyper-V supports: SCSI and IDE. There are two IDE controllers and four SCSI controllers available.

Each IDE controller can have two devices. You can not boot from a SCSI controller. This means an IDE disk will be required. The boot disk will be IDE controller 0 Device 0. If you want a CDROM it will consume an IDE device slot…

It wouldn’t be a problem if only virtual SCSI would provide no benefits over virtual IDE. But it’s quite the opposite:

…The IDE controller implements a well-known IDE controller and this means there is extra processing before the I/O is sent to the disk. This processing occurs in vmwp.exe (a user mode process that exists for each started VM. More on this in a later post). Once the IDE emulation is complete the I/O is sent into the Root Partition’s I/O Stack. I/O completion requires a trip back to vmwp.exe.

The SCSI controller is not emulated. The SCSI controller uses VMBUS (Virtual Machine BUS. More on this in a later post). The I/O’s pass from the Child (aka Guest) Partition to the root over VMBUS and enter the I/O stack. You can already see one less process/machine context switch is required because vmwp.exe does not get invoked. Once and I/O completes its completion is sent over VMBUS…

So performance bottleneck of virtual IDE and technical limitations of virtual SCSI will oblige customers to have two virtual disks for each VM. A configuration hard to setup in P2V migration scenarios, and hard to manage on large scale deployments.



blog comments powered by Disqus


virtualization.info Newest articles
Paper: VMware AlwaysOn Desktop Design Guide

April 23rd, 2015

VMware has released a paper titled: "VMware AlwaysOn Desktop Design Guide". The paper which contains 30 pages describes a high-availability solution for virtual desktops (VDI) and is based on View…

Book: Microsoft System Center Operations Manager Field Experience

April 22nd, 2015

Microsoft has released a free ebook titled:"Microsoft System Center Operations Manager Field Experience". System Center Operations Manager provides the monitoring component as part of the Microsoft System Center Suite….

VMware rebrands Immidio Flex+ as VMware User Environment Manager

April 22nd, 2015

In February this year, VMware acquired Immidio including its products AppScriber and Immidio Flex+. Now VMware has rebranded the product as VMware User Environment Manager.
User Environment Manager is available…

VMware announces 2 new products supporting Container virtualization

April 21st, 2015

VMware yesterday announced to new projects, Project Photon and Project Lightwave. Project Photon is a Linux Operating System which is optimized to run on vSphere and capable of running what…

Release: Docker Engine 1.6

April 21st, 2015

Docker has released version 1.6 of its container virtualization solution, Docker Engine. Also updates for Registry, Compose, Swarm and Machine and a preview of a client for Microsoft Windows…

Docker acquires Kitematic

April 16th, 2015

Lately it’s been a busy time for Docker, after disclosing the availability of its orchestration tools and the acquisition of SocketPlane, the open-source project that automates the deployment of…

Docker raises $95 million in Series D funding

April 15th, 2015

Docker, provider of the Docker container virtualization platform has announced that it has raised $ 95 million in a series D funding round. The round was led by Insight…

Paper: How VMware Mirage Complements and Extends Microsoft System Center Configuration Manager

April 14th, 2015

VMware has released a paper titled: "How VMware Mirage Complements and Extends Microsoft System Center Configuration Manager". The paper, which contains 28 pages details how VMware Mirage, VMware’s centralized image…

Paper: VMware Horizon 6 Storage Considerations

April 13th, 2015

VMware has released a paper titled: "VMware Horizon 6 Storage Considerations". The paper which contains 36 pages takes a close look at the most important questions and challenges that face…

Microsoft announces new container technologies

April 8th, 2015

In October last year, Microsoft announced that support for Docker container virtualization in its next version of Windows Server through the Windows Server Containers technology. Today Microsoft announced several…

Oracle announces beta for VM Virtualbox 5.0

April 7th, 2015

Oracle last week announced the availability of a beta for version 5.0 of its type-2 virtualization platform VM Virtualbox. VM Virtualbox, which was originally developed by InnoTek became part of…

Microsoft releases technical preview for VMware workload support by Azure Site Recovery – UPDATED

March 30th, 2015

Last week Microsoft announced new features for its Azure Backup solution. Azure Backup is a Microsoft solution which protects files and folders by providing multiple copies in multiple geographies….

Red Hat announces Q4 2014 earnings

March 30th, 2015

On March 25 Red Hat announced its financial results for the fourth quarter of 2014.
Total revenue for the first quarter ended February 28, 2015 was $464 million, with an increase…

Release: Oracle VM VirtualBox 4.3.26

March 25th, 2015

Oracle has released a new version of its virtualization platform VM Virtualbox. Version 4.3.26 is considered a maintenance release which can be installed on top of version 4.3. The update…

 
Monthly Archive