In order to fully leverage the benefits of both public and private cloud computing, it seems that some kind of hybrid cloud computing could be the viable solution many enterprises are seeking. By implementing a hybrid cloud strategy, enterprises perhaps manage to merge the advantages of private and public clouds, and escape the obviousdisadvantages. Let’s briefly examine some of the advantages and disadvantages for each cloud type:

Public clouds:
Although public clouds address many of the benefits enterprises are looking for, including the on-demand and elastic scaling, automatic provisioning, metering and pay-as-you-go mechanism – and in general to reduce capital expenditures, there are still several problems associated with public clouds.

Most of the concerns related to public clouds have to do with security and latency issues. From a security perspective, there are numerous potential vulnerabilities, both in the WAN networking domain and at a data center level. For example, in many cases the customer is sending unencrypted data via the Internet to a public cloud provider and has no idea of the data location, either within a particular virtualized data center or even without knowing at what data center his data resides. Most public cloud providers utilize virtualization to the fullest, meaning that it is very difficult to track data location as it can be migrating from one virtual instance to another. The strength of data isolation in a multi-tenanted public cloud environment is also sometimes disputable, especially if applications are not clearly isolated from the environment around it at all times. Additionally, latency can be a real concern when it comes to many real-time enterprise applications. Therefore, from an enterprise perspective, the majority of applications that have been migrated to a public cloud provider have been limited to non-critical applications and date, e.g. web servers and associated, CRM systems, storage and sometimes collaboration and productivity tools. Some providers are providing Content Delivery Networks to reduce the latency problem and bring content closer to the end-user, including Amazon with its Cloud Front and Rackspace with its collaboration with Limelight Networks.

Private clouds:
Establishing a internal private cloud environment (enterprise cloud) is another option for enterprises not interested or willing to trust the public cloud. As so many enterprises already have virtualized their data centers then certainly it should’tn be too difficult to transform the infrastructure to a Cloud based architecture, or what? It depends. Larger enterprises certainly can gain from a fully cloud-based infrastructure, providing IT scalability, automatic provisioning and cost granularity for individual divisions and departments, thereby adopting many of the Cloud benefits. Having said this, it seems inevitable that most enterprises will establish private clouds, right? Not so sure. Private clouds often lack the benefits of public cloud, such as by the following:

  • Requiring large investments in purchasing and maintaing IT infrastructure/resources and data centers
  • Lack of economies of scale – making own investments more expensive compare to a public cloud provider
  • Assuming over-capacity in IT resources to handle temporary peak-loads – leading to underutilization
  • Maintaining more highly qualified and costly IT experts in-house

However, when it comes to security and data privacy, many would conclude that private clouds are a much safer alternative. Although by no means a security guarantee, data would normally reside within the enterprise data center and therefore not be exposed to the dreaded “uncertain” data location and potential infringements, both due to WAN networking transport vulnerabilities and external data center conditions. This is certainly some of the issues vendors like IBM and HP are emphasizing – offering their enterprise/carrier class private cloud platforms (IBM Cloud Service Provider Platform and HP Cloud Start).

Hybrid clouds:
With hybrid clouds, IT managers can decide on what data and applications should reside within and be run in the internal private cloud and which should be “bursted” or moved to the public cloud. Minimizing resource overcapacity and balancing critical applications and data within the private cloud while moving peak-loads and less critical apps/data to the public cloud should me the goal.

API compatibility is another important issue. For example the Eucalyptus Enterprise Edition automates image conversion between supported hypervisors (WMware, Xen, KVM), including Amazon EC2 compatible AMIs (Amazon Machine Image). Several public cloud providers, including Terremark and Saavis, have also deployed WMware vCloud Express in their data centers, making it possible for enterprises that already use WMware’s virtualization technology (e.g. vSphere) to extend their private data center to a public cloud provider.

It seems likely that hybrid clouds will be an important element in making cloud computing more accessible and valuable for enterprises and that a hybrid cloud architecture will become increasingly important and deployed.

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