Getting the most out of your VMs
Virtualization is a hot technology, and for good reason. Today's virtualization products are mature, production-ready, and can be used to solve many problems that businesses face today. Here are 10 tips for using Microsoft Virtual Server 2005 Release 2 (R2) more effectively.
1. Upgrade to Virtual Server 2005 R2—First, upgrade to Virtual Server 2005 R2. Virtual Server 2005 R2 offers many new features, including 64-bit host support, support for Windows clustering services, new support for popular Linux distributions, fixed hyper-threading, and performance improvements of as much as 100 percent for Microsoft SQL Server and Exchange Server.
2. Allocate enough memory for your VMs—Memory is an important factor to consider when creating new virtual machines (VMs). When you size a VM, remember it will require at least the same amount of memory as the physical machine plus an additional 32MB for VM overhead. So, to adequately move a 512MB system to a VM you'd need to allocate 544MB of RAM.
3. Allocate enough memory for the host—Although it's vital to allocate enough memory for your VMs, it's even more important that you reserve adequate memory for the host. If the host runs out of memory and begins paging, the performance of all the VMs will suffer. 512MB should be considered the minimum amount necessary for the host. Running Virtual Server 2005 R2 on an x64 platform boosts the available memory as the supported system memory jumps from a 4GB maximum on the 32-bit platform to 1TB on the x64 platform.
4. Install Virtual Machine Additions—Microsoft Virtual Machine Additions is a component for improving VM performance and usability. Virtual Machine Additions provides high-performance mouse and video support by moving some important VM functions into the system kernel and enables optional host time synchronization.
5. Create your VHDs on a separate disk—VMs must share host resources, and the hard disk resource greatly affects performance. You'll reduce system resource contention and improve overall performance by creating Virtual Hard Disks (VHDs) on separate disk drives and even separating VM controllers from the drives and controllers that the host OS uses.
6. Use differencing disks to save disk space—You'll find that VMs and their associated VHDs can take up a lot of space. Using Virtual Server 2005 R2's differencing disks can significantly reduce the host storage requirements. Differencing disks enable you to create a read-only parent disk image that can provide the base for multiple other VMs, which saves a lot of host storage.
7. Remove VHDs from antivirus scanning—Antivirus scanning can drag down VM performance, so remove your VM's VHDs from antivirus scanning. This includes your .vhd, .vmc (VM configuration),.vud (undo disk), and .vsv (saved-state) files. Also, don't create your VHDs on encrypted or compressed volumes.
8. Open port 1024 for remote management—Unlike desktop-oriented VM products—which you typically manage via a Windows GUI—you manage Virtual Server 2005 R2 by using a Web interface, facilitating remote management of the server. By default, Virtual Server 2005 R2 uses port 1024 for the management console and port 5900 for the Virtual Machine Remote Control (VMRC) client. The VMRC client also uses ports 137 and 138 if Kerberos is in use.
9. Configure automatic VM startup—You usually want VMs to automatically start whenever the host system starts if your servers are consolidated. To configure automatic startup, open the Virtual Server Administration Web site, select the VM that you want to automatically start, and click Configure. Then, select General Properties and in the Action when Virtual Server Starts drop-down menu select Always automatically turn on virtual machine.
10. Take advantage of Windows 2003 R2 virtualization licensing—One VM-technology gotcha is that the OS used in a guest must be licensed as if it were running on a physical device. Windows Server 2003 Release 2 (R2), Enterprise Edition and Windows 2003 R2, Datacenter Edition provide a more cost-effective model for licensing Windows Server instances running in VMs. Windows 2003 R2 Enterprise allows as many as four active Windows Server instances, and Windows 2003 R2 Datacenter allows an unlimited number of active Windows Server instances.