As customers transition from phase 1 into phase 2 of their virtualization journey, they begin virtualizing business critical applications. As they move into this phase, they often perform a POC to understand how their application performs on physical versus a virtual platform. Customers often ask for guidance on conducting a POC and we talk to them about the importance of an apple to apples analysis. What I mean by this is making sure the physical server and the virtual machine are configured identically (or as identical as possible). One area we often find differences is in the number of processors a physical server has versus the number of virtual CPUs (vCPUs) you can assign to a virtual machine. Using the Microsoft System Configuration utility we can bring these two into alignment.
In our example, we will look at how to take a server that has 8 processors and 32 GB of RAM and configure this server to access 4 processors and 16 GB of RAM.
Below is a screen shot of System Properties screen and is accessible by clicking START > right click COMPUTER > Properties
From this screen shot we see the system has 8 processors and 32 GB of RAM.
Windows Task Manager, accessed by right clicking the Task bar, displays the same information.
Since we have determined the baseline for this analysis will be 4 processors and 16 GB of RAM, we will move onto configuring this server using the System Configuration utility.
First, click START > RUN > and type msconfig
This will open the System Configuration dialog box, and in this box click the Boot tab. On the Boot tab, click the Advanced options… button.
On the BOOT Advanced Options dialog box, check the box next to Number of processors and then use the drop down to select the number of processors you want Windows to be able to access. In this case we selected 4.
Next, check the box next to Maximum memory and enter the amount of memory you want Windows to access. In this case we entered 17,408 (17*1024) since we want the OS to have 16 GB usable memory.
Once satisfied with the configuration, click OK to close the BOOT Advanced Options dialog box, then click OK to close the System Configuration dialog box, and then click Restart to apply the configuration changes you just made
After the system restarts, log in and open Computer Properties by clicking START > right click COMPUTER > Properties
As you can see from the screen shot below, the system has 4 processors and 16 GB of usable RAM
Windows Task Manager, accessed by right clicking the Task Bar, displays the same information.
To remove these settings, open the System Configuration dialog box by clicking START > RUN > type msconfig
Next, click the Advanced options… button
And then uncheck the boxes next to Number of processors and Maximum memory.
Click OK on the System Configuration dialog box and then click Restart so your changes are saved. When the system reboots it will return to the original configuration.