The Advantages and Disadvantages of Private and Public Cloud Computing Solutions

Posted by Mark Teter, Chief Technology Officer
September 19, 2011

Cloud computing is still a relatively recent technological trend, and it’s certainly enjoying a ton of publicity and hype. All that aside, there are serious benefits cloud computing solutions can provide. Although each deployment option has its own benefits and drawbacks, in certain situations, the benefits can outweigh the risks. What you need to do is identify those situations in which you can apply the cloud to reap the maximum rewards with minimum risk.

Private clouds and public clouds are under the spotlight but it may be that a hybrid cloud computing solution is your best bet. To choose which cloud computing solution option is appropriate for your company, you’ll need to consider and balance a number of factors. We’ve weighed a few of the advantages and disadvantages between a public cloud— say Amazon EC2, in this case—and a private cloud at a co-located data center. This isn’t a comprehensive comparison by any stretch, but hopefully this can help move you in the right direction.

The three factors we’ll compare here are scalability, per-hour computing costs, and reliability and risk management. The ‘per-hour computing costs’ in this comparison are based on a three year purchase or lease. For a more detailed financial comparison of private versus public computing solutions, please visit our blog on the subject.

Public Cloud Computing Solution (Amazon EC2)

The scalability of a public cloud computing solution is typically very simple and immediate. The storage is also scalable to accommodate growth, and it’s easy to switch between performance categories. The downside is that there’s a higher cost per-hour that becomes aggregated with additional computing resources. Scaling up for increased performance can also multiply your cost by a factor of two or more, and there’s a fixed level of CPU and RAM per category.

The ‘per-hour computing costs’ for a public cloud is fairly easy and transparent; it’s OpEx versus CapEx and employee costs. The downside is that the costs are variable and subject to change at the whim of the provider. In addition, there’s no scalability within an instance—rather it’s per instance so you’ll need to watch costs carefully. Storage costs can also easily get out of control and are on top of computing costs, so you’ll need to monitor this carefully.

In terms of reliability and risk management, there’s little control over where systems are located or whether redundancy even exists. They’re also notoriously unreliable with little guarantee of uptime, as evidenced by Amazon’s fairly recent outage.

Private Cloud Computing Solution

If your private cloud solution is virtualized, you can scale it nearly as quickly as a public cloud offering with limited additional costs. You’d have CapEx costs, but they could be converted to OpEx costs through leasing options, and you’ll own your equipment at the end of the lease. The performance scaling is incremental—you can scale out, scale up, or scale within all quite easily. You can also easily maintain and support machines with different performance levels or a development and testing environment.

The only real downside to a private cloud computing option is that you must amortize costs if you purchase the equipment.

When calculated over a three year term, the ‘per-hour computing costs’ for both hardware and software are generally lower. You have the option to purchase or lease, and if you lease the equipment is yours at the end of the lease term.

A private cloud clearly differentiates itself from its public cloud counterpart in the reliability and risk category. With a private cloud, you can easily increase the level of support you need to cover power redundancy. Four integrated Gigabit Ethernet ports enhance network availability and can be installed in failover configurations. In addition, on-board system management tools encourage proactive remote monitoring and intervention.

Depending on your computing environment and needs, what levels of security and scalability you require, each cloud computing deployment option can play a role. Again, it might even be a hybrid cloud that suits your needs best.

About Mark Teter Before he retired from ASG in 2013, Mark Teter was Chief Technology Officer (CTO) and the author of 'Paradigm Shift: Seven Keys of Highly successful Linux and Open Source Adoptions.' As CTO, Mark regularly advised IT organizations, vendors, and government agencies, and he frequently conducted seminars and training programs.

Filed Under: Cloud Computing

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