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
Red Hat acquires FeedHenry

September 19th, 2014

We are living in a mobile world and the future will be more wireless than ever, we are working with technology all the time using our smartphones and tablets, the…

Citrix acquires Virtual

September 18th, 2014

Citrix yesterday announced that it has acquired Virtual. Virtual provides a virtualization platform for iOS and Android which is cloud based. Virtual provides a solution for testing applications without the…

Will HP buy VMware from EMC?

September 17th, 2014

Last week the New York times published an article titled: “EMC explores selling stake in VMware“. While the news that EMC is exploring selling VMware is not new though. Paul…

Docker raises $40 million in series C funding

September 17th, 2014

After raising $15 million in Series B funding in January this year, Docker has announced that it has raised $40 million in Series C funding. Docker states that it will…

Release: VMware Mirage 5.1

September 17th, 2014

VMware has released version 5.1 of its centralized image management for Windows desktops: Mirage.
VMware Mirage is also part of the Horizon Suite, VMware’s end user computing suite that includes…

Release: Proxmox VE 3.3

September 16th, 2014

Proxmox Virtual Environment (VE) is an open source virtualization management solution that leverages KVM technologies.
Yesterday Proxmox Server Solutions GmbH announced the release of version 3.3 of its product that…

Convirture opens a UK based office to explore EMEA market

September 15th, 2014

Convirture the company, founded in 2006 that provides an open source management console to manage virtualization platforms,  announced to have opened a UK- based office which will help the company…

Release: VMware ThinApp 5.1

September 12th, 2014

VMware has released version 5.1 of its application virtualization product ThinApp. Version 5.1 is the follow up of version 5.0 which was released in November last year. The update provides…

Brian Stevens former Red Hat CTO joins Google as VP of Cloud Platforms

September 12th, 2014

Two weeks ago we were wondering about Brian Stevens, who resigned as Red Hat’s CTO, asking ourselves if this could be seen as a “tremendous opportunity” for both.
Red Hat…

HP Acquires Eucalyptus

September 12th, 2014

Yesterday HP announced to have reached a definitive agreement to acquire Eucalyptus, provider of an open source Cloud Solution competing with OpenStack, CloudStack and OpenNebula.
This acquisition will put…

Release: VMware ESXi and vCenter Server 5.5 Update 2

September 12th, 2014

This week VMware released version 5.5 Update 2 of two of its flagship products, ESXi and vCenter Server, updates that were announced at VMworld 2014 in San Francisco.
Among the…

Release: Red Hat Satellite 6

September 11th, 2014

Satellite is Red Hat’s server life-cycle management based on the community project Spacewalk, it basically provides provision, patch, configuration and subscription management across Red Hat’s ecosystem.
Yesterday the Raleigh company…

Release: Oracle VM VirtualBox 4.3.16

September 11th, 2014

Oracle has released a new version of its virtualization platform VM Virtualbox. Version 4.3.16 is considered a maintenance release which can be installed on top of version 4.3. The update…

Microsoft releases limited preview of Migration Accelerator for Azure

September 8th, 2014

Microsoft last week announced a limited preview of Migration Accelerator (MA) for Azure. MA can seamlessly migrate physical, VMware, Amazon Web Services (AWS) and Hyper-V workloads into Azure, automating discovery…

 
Monthly Archive