Virtual Machines Best Practices

 • Deactivate screensavers: Screensavers consume CPU time. This consumption is relatively low, but if dozens of VMs run on the same server, this cumulated CPU time becomes significant. This is why deactivating them is preferable.

• Do not use a desktop background: Avoid desktop backgrounds. They also use CPU time and memory, often for no reason.

• Limit antivirus scans and automatic updates: Avoid scanning disks too often, and plan updates. Antivirus technology that scans disks too often can greatly affect performance. Disk scans should be planned to occur at specific times, avoiding periods of intense activity on the ESXi host server.

• Check the energy consumption options: In Windows 2008 Server, the option selected by default is Balanced. Change this to High Performance to fully exploit the VM’s performance.

• Optimize the size of the VM: Especially memory.

• Do not allocate additional virtual hardware: It can consume CPU time.

• Disconnect all nonessential ports such as the USB, serial, and parallel ports, and the disk or CD-ROM drives: Guest operating systems regularly access all devices, including CD-ROM drives. If several VMs communicate with the server’s physical CD-ROM drive, performance can be affected. It is preferable to use ISO image files.