JonRolfe.com

With VMware’s share price rising as much as 91% on the first day of trading, is this the future in IT or just another technology fad? It certainly has some advantages in many situations but it also has its disadvantages.

In development, prototyping or test environments it has huge advantages for allowing the rapid deployment of development systems and virtual networks. Virtual systems can be quickly regressed to a known point to aid testing and development. There are also advantages in application hosting environments where numerous legacy applications need to be supported but may conflict when running on a limited number of physical servers. There are also advantages of being able to fail over virtual servers between physical hosts in time of maintenance, and the ability to run different operating systems on a single workstation is obvious.

However in other situations it has its disadvantages. For instance, infrastructure servers (mail, DNS, database, domain controllers etc) can suffer from performance issues, or may not even be supported (897614, 888794) when running within a virtual server. Microsoft also limits support for problems occurring in virtual environments (897615), unless you’re running on Microsoft Virtual Server of course.

Servers, whether physical or virtual, still need to be patched, maintained, audited and clamped. So virtualisation won’t necessarily reduce the management requirements for a server, and it’s feasible that the management overhead and licensing costs may even increase as physical servers are consolidated to virtual servers running on multiple physical hosts. Finally, there even security concerns, as compromising the physical host would allow all the virtual systems running on that host to be compromised or causing a denial of service.

One area of virtualisation that has not gained much coverage, but could potentially produce the largest cost savings in management and consolidation, is the virtualisation of workstations. Although thin client solutions and “presentation virtualisation” as Microsoft refers to it (such as Citrix or Windows Terminal Services) have been available for many years, they have always had issues with application compatibility and performance. Many applications in the early days would not support being installed on Terminal Services and processor or graphic intensive applications would affect system performance for all users.

Performance and memory improvements with virtualisation technologies may solve these issues, and there are huge advantages in system management for workstations. Virtual workstation systems would be more secure as they would reside in a secure data centre rather than distributed across the enterprise. Also, where a session is compromised on a Terminal Services solution (such as through web based malware) it’s likely to compromise the entire service and affect all users on the server. In a virtual host it would be limited to the single host.

The main advantage however, would be in system management. Deploying frequent patches, large service packs or new application packages to workstations is a huge time consuming and bandwidth hungry exercise. Using virtualisation, this exercise is kept within the data centre, so reducing the bandwidth requirements. If a pool of virtual workstations is maintained, a number can be taken off-line at any time and patched without affecting the overall service. Finally, there is the reduction in cost for workstation hardware. Rather than providing costly workstations, these can be replaced with cheap thin clients that are used to access the centralised desktops.

Replacing physical desktops with virtual systems makes much more sense than virtual infrastructure servers, and this is why the announcement that Citrix is to purchase Xensource makes a lot of sense. Citrix will now be going head to head with VMware’s Virtual Desktop Infrastructure (VDI) while Microsoft is still trying, and failing, to gain market share on server virtualisation. The game has moved on, and while Microsoft has been busy trying to release a virtualisation solution to beat VMware (and have had to remove features just to bring it to market on time), a much better use of the technology has arrived.