This month I want to discuss server virtualization software. The products from VMware and Microsoft give some alternatives to server-based virtualization. If you're new to server virtualization, I suggest you start slowly. Consider virtualizing servers for a test lab or create virtual servers that don't have strict uptime requirements and that have minimal impact on business operations.

There are two major players in the virtual server software market: VMware and Microsoft. VMware has two products for server virtualization: VMware Server (formerly GSX Server) and ESX Server. VMware Server is available as a free download from http://www.vmware.com/download/server/ and has a feature set similar to Microsoft Virtual Server 2005. It has broad support for guest OSs, which makes it an ideal candidate to use for virtual lab creation, especially if you support several different OSs. It has limited support for some guest 64x OSs, compared with Virtual Server 2005, which supports only guest 32bit OSs. You install it over a host OS (Windows Server or Linux). Typically a host server running VMware Server has locally attached storage.

VMware has a beta product called Virtual Machine Importer 2.0 that converts virtual image files from GSX Server, Virtual Server 2005, Microsoft Virtual PC 2004, and Norton Ghost making it easier to convert existing server images into the VMware Server format without having to reinstall the server. It's available as a free download at http://www.vmware.com/products/beta/vmimporter/.

ESX Server is VMware's Enterprise class product that is designed to install in large data centers and co-location facilities. The ideal situation for ESX Server is an environment in which several host servers are connected to a Fibre Channel SAN. ESX Server is priced per host processor. The new x64 dual core/hyper threaded processors are treated as one processor. Typically you can consolidate four to eight virtual servers onto a single host. ESX Server loads a lightweight hardware specific kernel that provides near native hardware access to the guest OSs. Because the kernel is specific to each host server, it has limited support for host server hardware compared with VMware server and Virtual Server 2005. If you plan to use ESX Server, verify that your server hardware is supported by ESX Server. You can download a hardware compatibility guide at http://www.vmware.com/pdf/esx_systems_guide.pdf. If you're running on a SAN, check the guide at http://www.vmware.com/pdf/esx_SAN_guide.pdf to verify that your SAN is supported by ESX Server. Because of ESX Server's lightweight kernel, it has significantly less overhead and provides the better performance of the guest servers, than either VMware Server or Virtual Server 2005.

VMware will soon release a bundled package called VMware Infrastructure 3 that bundles ESX Server with added virtual server enhancements. It comes in three editions: Starter, Standard, and Enterprise. The Enterprise edition includes:

1. ESX Server.
2. VMFS--high performance cluster file system for virtual servers
3. VirtualCenter Agent--central management of virtual server farms
4. Virtual SMP--support for symmetric multiprocessor applications
5. Vmotion--lets an administrator transfer guest virtual servers to a different host without service disruption
6. VMware HA--high availability, SAN transparency, and Microsoft cluster support for virtual servers
7. VMware DRS--dynamically allocate virtual servers across the host server farm for optimized load balancing
8. Consolidated backup--perform full, incremental or image backups of virtual servers

This software's scheduled release is late June 2006.

Virtual Server 2005 is Microsoft's solution for server virtualization. It's available as a free download at http://www.microsoft.com/windowsserversystem/virtualserver/software/privacy.mspx. It runs on top of Windows Server 2003 or Windows XP (test environment only). There is an x64 version of Virtual Server 2005, however all guest OSs must be 32 bit. Virtual Server 2005 doesn't support Itanium processors. Microsoft has a Virtual Server Migration Toolkit that will create a virtual server image from a running physical server. This toolkit is available at http://www.microsoft.com/windowsserversystem/virtualserver/evaluation/vsmt.mspx.

Virtual Server 2005 integrates with Microsoft's management solutions. Microsoft recently released a Virtual Server Management Pack that integrates with Microsoft Operations Manager (MOM). It's available at http://www.microsoft.com/downloads/details.aspx?FamilyID=bf21f798-9b10-40dc-bcdd-4a8358cce94d&DisplayLang=en. This management pack lets you monitor both the host and virtual servers running on a host. Microsoft Systems Management Server (SMS) 2003 Service Pack 2 (SP2) includes some management integration with Virtual Server 2005 that will recognize the presence of Virtual Server 2005 and the discovery of virtual host/guest relationships. If you're a company that already has some of these Microsoft Network Management solutions installed, consider using Virtual Server 2005 as your server virtualization software.

Tip

If you're running Symantec Norton Antivirus (NAV) Corporate Edition 10.0 or Symantec Client Security 3.x eEye Digital Security has have identified a stack overflow problem that could potentially allow a hacker to execute remote code on a computer. Because this is such a big security risk, I suggest you upgrade all of your computers to the latest version as soon as possible. You can find out more about this vulnerability at http://www.symantec.com/avcenter/security/Content/2006.05.25.html.