Datacentre Virtualisation: Top Five Mistakes

Following are these five common mistakes and the means to effectively overcome these.

1.    Consolidating servers without guaranteeing fault isolation on the Application Delivery Controller (ACD) layer
The ability to consolidate multiple physical servers into a smaller number, each running multiple virtual application instances where each instance has full fault tolerance and computing resources isolation is one of the key benefits of datacentre virtualisation.

While the consolidation process is relatively standard, it becomes more complex when multiple ADCs (Application Delivery Controller) exist in the data centre, each providing delivery services to different applications.  As a result consolidation also involves the consolidation of the ADC layer.

The obvious solution is to reduce the number of ADCs with each one supporting more applications.  However, there is an inherent issue – the assurance of fault isolation in the ADC layer.  Incomplete fault isolation may result in the instability of one or more applications.

Solution: Use an ADC solution that guarantees complete fault isolation and resource reservation within the ADC layer.
2.    Virtualising business critical applications while disregarding the effects of a shared environment
Some IT managers choose to treat both critical and non-critical business applications the same way i.e., using the same virtualisation infrastructure for both. While this approach may be easier to manage because all applications sit on the same infrastructure, it creates potential issues for critical applications including quality of performance.

Moving an application from a dedicated physical server to a shared virtual infrastructure has the potential to degrade an application’s performance. This is because multiple applications must “fight” over the resources of a single physical server. While this may be fine for non-critical business applications, it is not for critical business applications.

Solution: Ensure an ADC solution is installed in front of all virtualised applications.  The ADC’s application acceleration capabilities e.g. compression, caching, TCP multiplexing, etc make it is possible to ensure the applications’ performance, thus providing end-users with the required level of service.
3.    Automating a virtual infrastructure without aligning the traffic distribution logic within the datacentre
Server virtualisation creates a single, consolidated infrastructure that enables multiple resources to be deployed at the same time. As a result, adding or removing VMs becomes easy and painless. Installing a new server in a traditional data centre environment can take several weeks. In a virtual environment the same server can be set-up within a few minutes. 

While an ADC solution guarantees the availability and performance of virtual applications, a network administrator needs to continually change its configuration in parallel to changes in the virtualisation layer. This may include adding or removing a new VM to a virtual application cluster for example. Failing to ensure the ADC’s configuration is up-to-date can result in degradation of the virtual application’s availability and performance.

Solution: To ensure the on-going alignment between a virtual infrastructure and the ADC, IT managers should implement an ADC solution that allows both the virtual infrastructure and the ADC to be monitored, automatically synchronising the ADC’s configuration with any change in the virtual infrastructure (VI). This will ensure the ADC continues to distribute traffic to applications, even when more servers are added.

Additionally, the solution needs to be able to grow on demand with the applications, so if more application servers are needed to support more end-user traffic, the ADC will follow.