Archive for the ‘Hyper-V’ Category

Windows 2008 Power Schemes and Performance Impact

July 11, 2011 1 comment

What is a Power Plan ?

A power plan is a collection of hardware and system settings that manage how your computer uses power. You can use power plans to reduce the amount of power your computer uses, maximize performance, or balance e two.

Power plans available with Windows Server 2008 are Balanced , Power Saver & High performance.

In Microsoft Windows 2008  &  Windows 2008 R2 Operating Systems , the default Power Scheme is set to be as Balanced which gives a balance between Performance and Energy Savings.

Doing some research on the impact of Power Scheme on Performance of Windows 2008 Hosts and specifically Hyper-V Hosts led me to multiple articles that has been referred below. Interestingly there is a well documented Microsoft Knowledge base article as well that you can find here. Although the KB does not say how much of an impact can the change have , there are some bloggers who have shared their testing result on the same.

Changing default power scheme from “Balanced” to “High Performance” has yielded 22% improvements in SQL performance that has documented by Glen out  here and Improvements in Hyper-V Performance can be found here. In our preliminary testing , we are seeing better results for Performance of  Hyper-V hosts that has been changed from default “Balanced” Power Scheme to “High Performance” Power scheme.

For people who are interested in Changing the Power scheme –

In a Full Installation of Windows Server 2008 , Open Control Panel –> Power options and you will be bale to select the Power Scheme of your choice

In a Core install of Windows Server 2008 , One can make use of powercfg.exe command to change the power scheme.

” powercfg -getactivescheme ” would dispplay the active Power Scheme in the Host

” powercfg -setactive 8c5e7fda-e8bf-4a96-9a85-a6e23a8c635c ” use this command to set the Power Scheme to High Performance

We are still doing our round of  testing to validate the improvements in Performance of Hyper-V hosts and Windows 2008 hosts due to Power Scheme. Would love to your experience and feedback as well.


Microsoft Hyper-V vs. VMware ESX

April 10, 2011 8 comments

This is not just another post to compare VMware ESX with Microsoft Hyper-V since i certainly believe without any doubt at this moment VMware ESX is leaps ahead of other competing hypervisors including Microsoft Hyper-V. What Microsoft has done with Sp1 for Windows 2008 R2 is introduce couple of cool features in Dynamic Memory and Remote FX to Hyper-V but these are not game changers. In this post , I am just trying to portray the  advantages and short comings of both ESX and Hyper-V.

What works for VMware ESX ?

  • Virtual Center, the management console of VMware for managing multiple ESX Servers generally does not get the credit it deserves. A single management console for managing , monitoring and patching of ESX hosts and the Guest VMs and it’s Applications makes administrator’s work easier.
  • Ability to configure Customized roles for administrators in Virtual Center.
  • Huge list of supported of Guest Operating Systems
  • Memory Management features such as TPS , Ballooning , Swapping and Memory compression.
  • HA & DRS Clustering capability of ESX is technologically superior to Microsoft’s Hyper-V Cluster giving the ability to provide high availability to VMs and at the same time distributing loads evenly across the hosts.
  • Fault Tolerance capability of VMware ESX
  • Third party plugin support from various vendors like EMC , NetApp , f5 , Dell etc.. that helps administrators manage them from Virtual Center
  • Advanced technologies like Storage vMotion , Storage IO Control , Network IO Control , Host Profiles and DPM ( Distributed Power Management)
  • VAAI (vStorage API for Array Integration)  helps offload the load of Storage related task on to Storage Array’s
  • Whole community of bloggers and lots and lots of free tools for VMware environment
  • VMware KB – Knowledge base site of VMware that is constantly updated and contains step by step resolution for most of the issues on VMware environment.
  • Stability/Resiliency of ESX

What VMware ESX lacks ?

  • There is no single management console for managing multiple free ESXi Servers. This can be achieved for Hyper-V using Hyper-V Manager..
  • Cost – Costlier when compared to Hyper-V but one has to consider the amount of features that comes packed with ESX which makes ESX worth every penny spent !!

What works for Microsoft Hyper-V ?

  • Microsoft recommends Hyper-V as part of their solutions and tight integration and support with various other products of the Microsoft Eco-system helps in adoption of Hyper-V.
  • Hyper-V Manager that helps in managing multiple Hyper-V Servers from a single console . Please note that there is limited functionality but still one can manage multiple Hyper-V Servers from a single console.
  • Cost ( Hyper-V is part of Windows 2008 family of products) – If the Virtual machines that run on Hyper-V are based on Windows , the cost associated with Hyper-V goes down dramatically since in a VMware environment we have to account the OS cost of VM’s as well.

What Hyper-V lacks ?

  • Dependency on multiple applications for managing ( SCVMM) , monitoring ( SCOM) and patching (SCCM/WSUS) of Hyper-V hosts and VMs and also the fact that there is no tight integration between these components.
  • Lack of Customizable roles for Administrators in Hyper-V Manager and SCVMM
  • Resiliency/Stability of Hyper-V cannot match that of ESX
  • Lack of advanced technologies supported by ESX like Storage vMotion , SIOC , NIOC , VAAI etc…

These are my personal opinion of what works for the hypervisors and what they lack ? Would love to hear your comments as well.

Post P2V Tasks

January 9, 2011 1 comment

P2V does not end with migrating a Physical Server to Virtual Server  but there are certain post P2V tasks that could help in improving the performance of the converted server. 

  • Ensure you install VMware Tools on the migrated VM without fail.
  • Remove all unwanted hardware components from a migrated virtual server like serial ports and floppy drives.
  • Change the CPU and memory of the VM as per requirement and do not go with default values as they reflect the resources as in the Physical Server.
  • Physical Servers are installed with OEM drivers which are resource consuming and these drivers can be removed using Add/Remove Programs once they have been converted to VMs.

I came across a HP utility that can be download from here  which can be used to remove HP PSP with a single click.

One of the issue that is reported is the error when they get when try to assign IP to the migrated server –  ” The IP address XXX.XXX.XXX.XXX…” is already assigned to another adapter”.

This error message is caused by Ghosted NIC Cards that are present. These are the NIC cards that are converted as part of the P2V process since they were part of the physical Server but does not show up on the device manager. Follow the below mentioned steps to uninstall the ghost NIC cards.

  • Click Start –>Run–>Cmd [ Open a Command prompt]
  • Type in “set devmgr_show_nonpresent_devices=1” [ This change would display all non-present devices in device manager]
  • From the command prompt, type in “devmgmt.msc” [Do not go to Run prompt to open device manager or open from a GUI since above change would be effective from cmd prompt only]


  • Click View –>Show Hidden Devices
  • Non-Present devices are grayed out and can be uninstalled from the server. In this case  out NIC cards has to be uninstalled.


  • Now try assigning the IP back to the NIC card in the Virtual Server and should work fine.

IP Address issue has been addressed by Microsot here and VMware here and lot of other bloggers too.

Troubleshooting a Hyper-V VM struck at Starting during Boot-up

October 7, 2010 Leave a comment

Post restart of a Windows 2008 R2 Hyper-V Server which hosted some critical VMs , One of the VM went into Starting state . Basically the VM was struck in Starting status both in Hyper-V Manager as well as in SCVMM Console and the VM was not responding . Right Click on the VM didn’t help as the only options that was available were Connect,Rename,Settings & Help .

On investigating the event viewer of the Hyper-V Server , I identified  instances of vmms.exe crashing as shown below .

First , I tried restarting the Hyper-V Services but did not help my cause as the VM was still struck . Next tried to restart the server but still the VM was struck at Starting state post reboot. Some Googling  led me to this Microsoft KB that would help me fix this issue permanently but also found an alternative solution that would help . I logged into the Hyper-V Server and had a look at the task manager to see the status of the VM Worker Process .

As you see above ,  one of the vmwp.exe (Virtual Machine Worker Process ) process was using around 5K of Memory ( Private Working Set ) whereas other vmwp.exe was using 14K of Memory . Hoping that this might be the worker process for the VM that was struck , I tried killing the process so that i would be able to restart the VM but to my surprise , the frozen VM now automatically powered on itself !!

Categories: Hyper-V Tags: ,

My Wishlist for Hyper-V

August 26, 2010 Leave a comment

As part of my work, I get to work on VMware Virtual Infrastructure as well as Microsoft’s Hyper-V environments and there is a lot of difference that one cannot ignore with a blind eye . VMware for sure is way ahead in the race as far as Server Virtualization is concerned. Knowing Microsoft , I am sure they will do everything possible to catch up with VMware in the race . They have already announced Remote Fx and Dynamic Memory as part of their SP1 for Windows 2008 R2.

So here goes my first set of Wish list for Microsoft’s Hyper-V and SCVMM . These are some basic feature requests that would help Hyper-V Administrators world over :

  • Integration of SCOM , SCCM & SCVMM into a Single management console should do a world of good for lot of Hyper-V Administrators. Today we are dependent on three different products for managing Hyper-V.
  • Role based access for System Center Virtual Machine Manager / Hyper-V Manager.
  • Providing GUI based tools for configuring Hyper-V running on Server Core .
  • Improving Integration with Third party backup products.
  • Improving the mechanism in which snapshots are handled today in Hyper-V.
  • Make Technical Documents on Hyper-V more accessible to the end users .
  • Increase the number of Third party tools available for managing  Hyper-V environments.
  • Increase the number of Guest Operating Systems that are supported on Hyper-V.

So What’s your wish list for Microsoft Hyper-V ?

Be-Aware of Hyper-V Snapshots

August 25, 2010 4 comments

Snapshots capture a state of a Virtual Machine, data and hardware configuration. VMware ESX and Microsoft Hyper-V hypervisors provides the ability to take snapshots but the mechanism used for handling the snapshots are completely different and understanding them is very important.

Recently we faced an issue in one of our test Hyper-V Server where all the machines went into a saved state. We narrowed down on the root cause and found that there was no space available on the drive hosting the VMs. When we dived further, we found that there were huge .AVHD files on one of our Virtual machine. We immediately checked the Hyper-V manager for active snapshots but there were no active snapshots. We had taken snapshots for that Virtual machine that was active for a week and then deleted the same from the Hyper-V manager.  Now some search on Google led me to Microsoft’s FAQs on Hyper-V VM Snapshot on TechNet.

This is when I realized that mechanism implied by Hyper-V on snapshots is completely different from VMware ESX Server and ESX handles snapshots better than Hyper-V. So here are my key learning’s that I hope would be helpful to everyone working on Hyper-V.

  • When we delete a snapshot present in a Virtual machine from the Hyper-V Manager, the .AVHD files that contains the snapshot data remains with the VM until the VM is shut down / Saved / Powered Off. Hyper-V Manager displays the progress when deleting the snapshots. After the merge is complete the AVHD is deleted by the system.
  • Do not delete the AVHD files directly from the storage location. This will cause your Virtual machine to go down.
  • Do not expand a virtual hard disk when it is used in a virtual machine that has snapshots. Doing so will make the snapshots unusable.
  • The presence of a virtual machine snapshot reduces the disk performance of the virtual machine.

Now back to our problematic Hyper-V Server, we powered off the VM and waited patiently for the AVHD files to merge back with the base disk and after a long wait the process got completed. Now we were able to power on back all the Virtual machines hosted on the server.

How can we afford to take a downtime for a Virtual Machine just to commit a snapshot?

What happens when I run out of disk space since I will need space to allow the merging of disks used in snapshots?

VMware snapshots has been discussed extensively in this VMware KB article and Snapshots in Hyper-V has been discussed in detail in a series of blog posts that can be found here and here and here .

Hoping that Microsoft will improve the mechanism in which the snapshot is committed in a Hyper-V Virtual machine.

Categories: Hyper-V Tags: , ,

Removing an Orphaned Hyper-V Host from SCVMM

August 12, 2010 1 comment

We were unable to remove one of our Hyper-V hosts from SCVMM as it would throw an error stating that SCVMM was unable to communicate with the Hyper-V host . We had reinstalled the Hyper-V Server without removing it from SCVMM before the re-installation process. This left an orphaned Hyper-V host on the SCVMM .

Google search led me to a Technet post which suggested to use ” -Force ” switch using the Power Shell option available in SCVMM and Voila !! We were able to remove the host from SCVMM , Finally !!

Steps are pretty straight forward :

Login to SCVMM

Click on the Power Shell icon available on the top of the screen and use the below mentioned command

Get-vmhost Hyper-V Hostname| remove-vmhost –force “

Please note that the above command can be used when we do not remember the Credentials for the host as well as in scenarios where the SCVMM and Host are unable to communicate. When we  use  the Force parameter, VMM does not prompt for or check credentials, and VMM does not attempt to connect to the host and uninstall the VMM agent .

Categories: Hyper-V Tags: ,