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Depending on the source, private clouds are either going the way of the dodo or they’re growing faster than a bullet train. The reality is that true private clouds, as opposed to merely virtualized data centers, are becoming more popular. Infrastructure that IT mistakenly termed a private cloud is not, since hypervisors alone cannot provide all of functionality that any cloud needs, private or not.
According to NIST (National Institute of Standards and Technology), cloud functionality must include five features: shared resource pools, scalability, self-service on-demand, a way to measure services, and network access. Simple enough, one would think – if some vendors stopped advertising products as a private cloud when they are not.
There are of course distinct differences between cloud types. Let’s look briefly at four common models of cloud: private, vendor, public, and hybrid.
· Private cloud. This infrastructure is provisioned to serve corporate users. In its strictest sense, the private cloud resides behind the corporate firewall in the customer’s data center. Although virtualization does not a private cloud make, it is an enabling technology for the cloud. Virtualization enables the organization to provide the necessary level of dynamic provisioning, service additions and scalability using existing infrastructure. Private cloud software integrates with the virtualization layer, and provides the self-service portal and management layer for users and cloud administrators.
· Managed private cloud. This model hosts multiple accounts with customer-dedicated server and storage resources. Support levels differ by customer requirements. Customers lose a level of control and geo-specific cloud storage, but gain third party services. Examples include Amazon Virtual Private Cloud (VPC), and Rackspace managed private cloud using the external cloud option. Some managed cloud providers maintain customer data behind the corporate firewall and provide the control plane from an external location. Platform9 is an example.
· Public cloud. The public cloud is provisioned for public usage as a service. Customer applications and data share the multi-tenant infrastructure and are logically segregated. Public cloud scalability is near-infinite. AWS, Google Cloud and MS Azure are leading providers.
· Hybrid cloud. As the name applies, a hybrid cloud architecture is made up of two types of cloud, usually a private cloud with integration to a public cloud. The infrastructure is integrated for seamless (or relatively seamless) operations between the two. Microsoft Cloud is an example of a hybrid cloud combining MS Azure, Windows Server, and System Center for a private-plus-public configuration.
· Vendor cloud. This cloud delivers specific vendor services to customers. An example is Zetta.net, which provides its own cloud for its data protection customers. Vendors may build their own cloud data centers or lease space on large providers like Rackspace or AWS.
Private Clouds: Advantages and Cautions
What the private cloud does best is host critical Tier 1 applications that require high performance, high security, strict governance, and near-zero RPO. This makes the private cloud ideal for high value usage cases such as high performance access to mission-critical data.
An on-premise cloud may take more staff time and expense than a cloud installation (although that is not always the case). However, the private cloud grants the strongest possible oversight over corporate data. Governance benefits from distinct geographical locations and the ability to audit data movement, creation and modification. Private clouds also meet data storage regulations that may not allow for the public cloud. Security is another benefit. Public clouds have layers of security but they still have multi-tenant installations, and may not have optimal data encryption.
There is no question that the on-premise private cloud is faster than transferring data to and from a remote cloud site. The private cloud also gives the corporation better control over noisy neighbors – applications that grab server, network and storage resources. The business will have little control over noise in a multi-tenant infrastructure other than complaining to the provider.
The enterprise can also customize their private cloud to best suit corporate needs. Businesses can and do work with cloud providers to meet SLAs, but the provider may be unable or unwilling to meet them. In contrast, the private cloud is fully customizable according to the organization’s needs. The organization also avoids vendor lock-in with a true private cloud, since him more data and services that the business entrusts to a cloud provider; the harder it is to migrate to a better service.
What are the Drawbacks?
No cloud choice will be perfect in every detail and private clouds are no exception. Private cloud owners should be aware of CapEx and OpEx. Capital costs can be steep because of hardware requirements. Even when organizations leverage existing equipment to build the initial private cloud, scalability and flexibility will require upgrading capacity and performance over time.
The organization should also calculate how expensive it will be to operate the private cloud and what kind of burden it adds to IT responsibilities. The organization will also be responsible for energy and data real estate costs.
Private Cloud Vendors
Private cloud offerings are not as common as public or hybrid cloud services, especially if we look exclusively at vendors who have an on-premise-only option as opposed to managed private clouds. Many vendors are coy about how they define the private cloud, choosing to say that they support a private cloud but meaning either managed private clouds or hybrid clouds – in both cases, requiring an external component for the private cloud.
OpenStack is an open source architecture with widespread server, storage, and hypervisor support. OpenStack is not itself a cloud but is a cloud service framework, which enables many cloud models, including private clouds. We do not suggest adopting OpenStack alone without development expertise, but additional products and technologies fill in the gaps such as SwiftStack or Apache CloudStack. HP Helion CloudSystem Enterprise for private and hybrid clouds is also based on OpenStack.
VMware vCloud Suite Private Cloud turns a virtual layer into a private cloud. It’s full-featured with VMware but also supports Hyper-V and Xen. vCloud Suite combines a number of technologies to work, which can make for a complex licensing and upgrades. The core suite includes vSphere and vSphere Site Recovery Manager along with a set of management products and expansion options including vSAN and OpenStack.
From the hardware provider side, Dell offers preconfigured private clouds based on VMware, Hyper-V or OpenStack. Dell provides modular storage, networking and server products along with Dell Cloud Manager and Boomi. Intel runs a cloud partner initiative that provides reference architectures based on Intel Xeon processors to ISV and OEM partners. For example, Intel partner Amax offers a private cloud built on Intel Xeon E5-2600 running CloudMax and VMware vCloud Director.
Private Clouds: Going Forward
Choosing a private cloud is not an either/or proposition. The enterprise may adopt one or more cloud models depending on the need. Public clouds work well for long-term data storage, web application data delivery, and remote hot sites with virtual failover. Vendor clouds support software offerings, while hybrid clouds can deliver best-of-breed services.
The private cloud does not exist in a vacuum, and may benefit from access to an external cloud for operations like data protection or cloudbursting. The question is not whether to adopt a private cloud and nothing else. It is whether to keep or give up direct control over the enterprise cloud. If the organization has a comfort level with public or hybrid clouds then a private cloud may not be necessary. If, however. the organization has high value data and important governance needs, a private cloud offers big benefits.
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