Performance Optimization for VMs
Collating together best practice tips for getting best performance from your VMs:
1. Software optimization:
Install the latest Virtual Machine Additions: for Windows Server 2003 SP1 go here https://www.microsoft.com/downloads/details.aspx?FamilyID=a963433c-193b-41ac-af6e-ab7ab2db8541&DisplayLang=en
Configure the Windows Server 2003 host operating system for “Best Performance“ under Performance Settings in the System Properties . Configure services priority to for “Background Services“:
Right-click “My Computer“, click Properties. Click Advanced tab. Select “Settings“ under “Performance“.
Exclude the Virtual Server services - VSSRVC.EXE and VMH.EXE from host anti-virus software scanning.
Dedicate the box: Do not run other programs on the host
2. Memory Optimization: Install additional RAM in the host computer. The amount of RAM in the host computer limits the number of virtual machines that you can run in Virtual Server 2005 more than any other factor. The host operating system and each running virtual machine require sufficient memory. To calculate the total amount of memory that you require, tote up:
operating system on each virtual machine.
programs that run on each virtual machine.
operating system on the host computer.
add up to 32 megabytes of additional RAM on the host computer for each running virtual machine.
For example:
Physical or virtual machine |
Operating system |
RAM allocated to OS |
RAM allocated to virtualization |
Total RAM required |
Host computer |
Windows Server 2003 |
512 MB |
512 MB |
|
Virtual machine 1 |
Windows NT 4.0 Service Pack 6a |
128 MB |
32 MB |
672 MB |
Virtual machine 2 |
Windows NT 4.0 Service Pack 6a |
128 MB |
32 MB |
832 MB |
Virtual machine 3 |
Windows 2000 Service Pack 4 |
256 MB |
32 MB |
1120 MB |
Virtual machine 4 |
Windows 2000 Service Pack 4 |
256 MB |
32 MB |
1408 MB |
Virtual machine 5 |
Windows Server 2003 |
512 MB |
32 MB |
1952 MB |
Virtual machine 6 |
Windows Server 2003 |
512 MB |
32 MB |
2496 MB |
Virtual machine 7 |
Windows Server 2003 |
512 MB |
32 MB |
3040 MB |
Virtual machine 8 |
Windows Server 2003 |
512 MB |
32 MB |
3584 MB |
3. CPU optimization: Install additional CPUs in the host computer. Disable Hyperthreading if the host has support for it.
4. Disk optimization:
Use a fast hard disk subsystem in the host computer. 10K RPM drives are relatively cheap these days.
Use virtual SCSI hard disks instead of virtual IDE hard disks
- make sure you configure the correct drivers
- you may have to manually upgrade the drivers
Use fixed-size virtual hard disks instead of dynamically expanding virtual hard disks
Run VHD files from a different physical disk than the host OS. RAID 0 will help when writing large files. RAID 5 will also improve performance especially on READ operations. RAID 1+0 will be the best of both worlds.
Schedule host Defrag during idle time.
See: https://support.microsoft.com/default.aspx?scid=kb;en-us;903748 and https://blogs.technet.com/brucecowper/archive/2004/12/22/330223 and https://support.microsoft.com/kb/840575/en-us