Windows 2008 Power Schemes and Performance Impact

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.

Verifying File Integrity using MD5 Checksum

What is MD5 Checksum ?

According to Wikipedia ,  MD5 Message-Digest Algorithm is a widely used cryptographic hash function with a 128-bit (16-byte) hash value. Specified in RFC 1321, MD5 has been employed in a wide variety of security applications, and is also commonly used to check data integrity.An MD5 hash is typically expressed as a 32-digithexadecimal number. MD5 is more commonly used these days and is used to ensure the file integrity of files that we download.

How to verify MD5 for files that we download ?

Even though there are many tools to verify MD5 , I prefer the Microsoft FCIV (File Checksum Integrity Verifier) Utility which can be download from here.Fciv is a command line utility that computes and verifies hashes of files.It computes a MD5 or SHA1 cryptographic hash of the content of the file.

The FCIV utility has the following features: Supports MD5 or SHA1 hash algorithms (The default is MD5.) Can output hash values to the console or store the hash value and file name in an XML file Can recursively generate hash values for all files in a directory and in all subdirectories (for example, fciv.exe c:\ -r) Supplies an exception list to specify files or directories to hash Can store hash values for a file with or without the full path of the file Let’s try FCIV Utility to verify MD5 & SHA1 SUM for a vSphere Hypervisor Download. Setting up FCIV Utility : Download FCIV Utility “Windows-KB841290-x86-ENU.exe “ Double click Windows-KB841290-x86-ENU.exe and extract it to a folder Add the FCIV folder to the system path or else every time you execute FCIV, one has to browse to the folder where  FCIV Utility has been  extracted . Go to command prompt and type fciv.exe /?, and then press ENTER to see the various options. Ensuring File Integrity would mean that MD5 or SHA1 SUM value displayed on the website should match with that of the downloaded file. In our case , VMware ESXi 4.1  download page tells me the MD5 and SHA1 SUM value for the ESXi 4.1 Update1 ISO image. Once the download is complete , Open a command prompt and calculate the MD5 or SHA1 SUM as shown below using the FCIV utility . fciv -add  -md5 fciv -add  -sha1

Post P2V Tasks

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.