Managing server virtualisation

The principle of server virtualisation is now pretty well accepted in the mainstream IT professional community, but Andy Buss, Tony Lock and I have been having a lot of conversations with IT professionals recently suggesting that software licensing can still be a problem.

On quite a few occasions, we have each heard stories about consolidation initiatives that have got bogged down in wrangles about the commercial and legal aspects of software deployment.

While most of the experience gained is from consolidation projects at the moment, thinking beyond these to the creation of more dynamic virtualised environments, ultimately to private cloud, the difficulties are likely to become even more pronounced.

After so many years of physical and virtual server hosting being an integral part of mainstream IT, it's telling that many are still struggling to determine what's legal and most cost effective in this context too.

When you analyse things, based on all of the input we have received, two basic problems exist:

1 The undermining of the link between value and cost when virtualisation technology is used to partition servers.
This arises because virtual servers generally only use a subset of the underlying physical server resources available. Sometimes this is implicit, as applications compete for shared resources, other times it's more explicit, when a virtual machine (VM) is only allocated access to two CPUs in a four way box.

The emergence of multi-core and multi-threaded processors, and the option to allocate fractions of CPUs or cores to VMs, then complicates things further.

Some vendors have ignored all this and insist on charging a licence fee based on the full physical spec of the host machine. This approach is now less common than it used to be, but when it is applied it can restrict flexibility and/or lead to quite punitive costs that many consider to be unfair.

Others vendors have attempted to deal with the issue, but often in a manner that is difficult to understand or administer, and typically employing approaches that err on the side of their interests rather than their customer's.

2 The flexibility that stems from decoupling the software layer from the physical server.
In a virtualised environment, applications are no longer tied to a specific machine, so the hardware underpinning a software installation is no longer necessarily persistent. Even in a manually administered setup, the ease with which virtual servers can be relocated between physical boxes means operations staff have a lot of freedom to optimise resource usage.

They are increasingly taking advantage of this as requirements evolve and hardware is naturally refreshed. But much of this activity is not catered for by traditional software licence terms.

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