Some people argue there are still some applications that should not run on virtualised servers, but that assertion is surprising given the shift to the cloud, says Lori MacVittie.
Two trends are taking place that appear to be at odds with each other. On the one hand, interrelated approaches, including virtualisation and cloud-enabled services, are driving the shift towards organisations owning less hardware, as set out in a briefing note from analyst firm Gartner.
On the other hand, the adoption of virtualisation, though widespread, still accounts for less than 40 percent of all servers in datacentres today. What makes this particularly interesting is Gartner's prediction that "by 2012, 20 percent of businesses will own no IT assets."
Conflicting trends
These trends appear to conflict because most applications being deployed in the cloud today rely on virtualisation, yet organisations are not entirely sure that all applications should be virtualised.
It seems unlikely Gartner's prediction will even come close to becoming reality. A CDW report highlights why organisations are not virtualising more applications, including the view that "some applications may not be supported by their vendors in a virtual state".
So the future of cloud computing seems dependent on the successful virtualisation of custom and packaged applications. Given the concerns about virtualisation cited by CDW, one may be tempted to conclude that for cloud and virtualisation to maintain momentum or increase adoption rates, applications will have to become virtualisation-aware.
Direct access
Microsoft defines virtualisation-aware implementations as applications that directly access hypervisor core architectures, bypassing the device emulation layer.
For example, Microsoft describes 'enlightened I/O' as "a specialised virtualisation-aware implementation of high-level communication protocols, such as SCSI, that utilise the VMBus directly, bypassing any device emulation layer. This [approach] makes communication more efficient but requires an enlightened guest that is hypervisor- and VMBus-aware."
Read this
Cloud Watch Special Report
Untangle the hype and the promise, the good and the bad, the risks and the benefits of cloud computing
Similar mechanisms are provided by VMware that can improve performance and reduce the overhead associated with the virtualisation of applications.
Reduced overheads
So virtualisation-aware applications are those that know they are running in a virtualised environment and bypass the emulation layers to reduce the inherent overhead associated with such layers of abstraction, thus improving application performance and, ultimately, the efficiency of the virtual machine.
Virtual-machine efficiency is important because it affects virtual-machine density — that is, the number of virtual machines that can effectively be running on a given hardware platform.
But this process is not trivial. Applications need to be rewritten to be virtualisation-aware and, if they are, they will not necessarily...
Talkback
My only twinge about the idea of apps being specially written for one particular virtualisation platform is that developer effort then goes into than rather than making the app better for everyone else, not all of whom will be using Hyper-V.
Maybe that is one element of Microsoft's strategy...