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
VMware acquires Wanova

May 23rd, 2012

Yesterday VMware announced the acquisition of Wanova Inc. a company whose main product is called Mirage.
Mirage is a centralized management and recovery solution for physical desktop images over the…

Paper: VMware vSphere Metro Storage Cluster Case Study

May 23rd, 2012

Yesterday VMware published a paper focused on VMware vMSC (vSphere Metro Storage Cluster), a new configuration within the VMware Hardware Compatibility List intended for environments where disaster/downtime avoidance is a…

EMC acquires Syncplicity

May 22nd, 2012

Yesterday, during its annual conference in Las Vegas, EMC announced the acquisition of Syncplicity, a cloud-storage privately held startup founded in 2008 and based in Menlo Park, California.
Terms…

Release: Oracle VM Server for x86 3.1

May 21st, 2012

On May 18th Oracle announced the general availability of version 3.1 of its x86 enterprise virtualization solution VM Server.
This release follows 3.0 announced on August 24th 2011.
All the new…

VMware shows View 5.1 performance improvements

May 21st, 2012

In this post, published on May 18 in VROOM! Blog, the VMware’s Performance Team presented some of the most significant enhancements and optimizations brought to Teradici‘s PCoIP protocol in the…

NVIDIA introduces World’s Firs Virtualized GPU

May 17th, 2012

On May 15th NVIDIA unveiled the NVIDIA® VGX™ platform that will be available later this year through NVIDIA’s hardware OEM and VDI partners.
This new platform promises to deliver…

Microsoft announces Assessment and Planning Toolkit 7.0 Beta Program

May 17th, 2012

Microsoft announced this week the new Beta version of its capacity planning tool Microsoft Assessment and Planning (MAP) 7.0 Beta.
The Beta program opened on May 15th and the review…

VMware announces vFabric Suite 5.1

May 15th, 2012

Today VMware announced VMware vFabric Suite 5.1, expected to be generally available in Q2 2012.
vFabric Suite 5.1 includes vFabric Application Director, to automate the deployment and management of vFabric…

VMware CTO talks about R&D plans for the future

May 15th, 2012

On April 4 Stephen Herrod, VMware’s CTO, has attended, as guest speaker, at a VMUG meeting in Italy.
One of the key point of the speech, documented in one hour-long…

Citrix Hosted Server VDI Tech Preview

May 14th, 2012

Last week Citrix announced a new tech preview for Hosted Server VDI technology that allows cloud providers to leverage Microsoft SPLA to host VDI-style desktops obtaining a pay-as-you-go monthly subscription licensing…

Release: Atlantis ILIO Diskless VDI 3.2

May 11th, 2012

On May 7 Atlantis Computing announced the general availability of its Atlantis ILIO Diskless VDI 3.2, this product, tailored in particular for VMware View 5.1, enables virtual desktops deployment…

Citrix unveils Project Aruba

May 11th, 2012

On May 7 Citrix announced a technology preview of Project Aruba that extends Citrix VDI all-in-one proposal for the SMB market, VDI-in-a-Box, with personal vDisk technology.
VDI-in-a-Box, inherited from Kaviza…

Cloud Sidekick announced Early Access release of Cato EE

May 10th, 2012

On May 7 Cloud Sidekick announced the Early Access Program release of Cato Enterprise Edition (EE) which extends the Community Edition (CE) with Storm Deployment Automation and support for…

Release: VMware vCenter Infrastructure Navigator (VIN) 1.1

May 9th, 2012

On April 26 VMware announced the general availability of VMware vCenter Infrastructure Navigator (VIN) 1.1, previously introduced as a part of vCenter Operations Management Suite.
VIN automatically detects, discovers and…

 
Monthly Archive