Openstack and Testing servers


OpenStack is not a hypervisor, it is a set of components that comprise a cloud computing platform, and can run on top of any one of six hypervisors. While it is well suited to small clusters, it has only one key benefit beyond simple VMs:
 
OpenStack provides API-driven provisioning of computing resources to support self-service, on-demand use.

In my opinion, running OpenStack nova (the compute, networking and volumes component) on anything less than 3-4 reasonably beefy servers is more trouble than it's worth - unless you're specifically geared towards supporting users familiar with cloud computing concepts and tools.

Generally speaking, the OpenStack storage component (swift) is not reliable without a minimum of three separate servers, preferably more.

There are extensions to OpenStack (proposed and under development) that would allow it to manage more of the 'cloudbursting' functionality typically handled by elasticity managers such as Scalr, RightScale, etc. When those hit prime time, this may be worth re-evaluating for just that reason.

While I make frequent use of open source software, I would recommend using enterprise (but free) solutions from one of the three industry-leading type 1 hypervisors.
  •     VMware ESXi (http://www.vmware.com/products/v...)
  •     Microsoft Hyper-V (http://www.microsoft.com/hyper-v...)
  •     Citrix XenServer (http://www.citrix.com/English/ps...)


Not only are these solutions widely used, they may be easily upgraded to a fully licensed and supported enterprise solution by purchasing and inputing product keys. That way if your test environment is successful and you want to put it into production, the process will be much easier.
Oother choice is OnApp http://onapp.com/onapp-overview.

Unfortunately not open-source, the cost is $10 per CPU core, but you get 100 cores free for the first year plus free setup, integration and 15 minute SLA support. Licensing page with all details http://onapp.com/onapp-pricing/.