A private cloud takes the core principles of cloud computing and combines them with more traditional colocation services to create a new, single-tenant, virtualised environment. With a private cloud, the customer rents a package of X physical servers, Y virtual machines and Z storage resource, often delivered in dedicated colocation racks.
Private clouds typically have the following attributes:
- Fully managed service – provider provides configuration
- Firewalling and load balancing provided as part of solution
- Minimum contract term, usually 3 to 5 years
- Scalable within the parameters of the physical hardware
- Instance size varies by individual customer
- Typically Windows or Linux OS options
With a private cloud, the service provider is responsible for building and managing the cloud, with the virtual machines being managed under the same “hypervisor” as the VMs on their multi-tenant platform. This saves the customer the cost of the virtualisation and hypervisor software licenses and removes the hassle of building and supporting the cloud.
A high-level virtual private cloud deployment is shown below:
Advantages of Private Clouds
Private cloud customers typically choose this option because they have a preference – due to compliance, regulation, governance, security or culture reasons – for dedicated hardware in a single-tenant configuration. The standard cloud computing benefits still exist, albeit in a limited fashion, with the customer having the comfort of knowing that their equipment is only, and can only, be used by them. They are invariably sourced via a managed hosting/managed services approach, with upfront design work needed, and a long term contract in place. For many, this gives a comfort factor of having long-term visibility of costs and a managed hosting model based on stringent SLAs and performance criteria.
Disadvantages of Private Clouds
Private Clouds are, by definition, restricted. Thus, they lack the extreme scalability and elasticity of public clouds but many companies do not need this capability as they have no seasonality built into their business or only require these on a smaller scale. In order for the solution to be financially viable, the contract lengths are typically in years, as opposed to the months, weeks or even hours that are available with some public cloud services. Note that many private cloud customers still use public or virtual private cloud solutions as part of a hybrid cloud with them “bursting” onto a multi-tenant platform when their single-tenant private cloud does not have the necessary capacity.
Examples of Private Cloud in the Real World
Private Cloud usage models are typically the same as virtual private clouds but are used by customers who need or prefer a dedicated, single-tenant environment.