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Some AWS customers evaluate cloud vs. on-premises options

Large technology shops that rely on AWS infrastructure have to weigh several competing issues in choosing cloud services. Cost is a reason to leave AWS, but it's not the only one.

Some big companies, including technology-focused enterprises, can outgrow AWS' public cloud capabilities. This...

might come as a surprise to some AWS customers, but if it happens to an enterprise, the real question isn't whether to choose cloud vs. on-premises infrastructure, but rather how much will it cost to leave AWS?

Earlier this year, Dropbox made the move off of AWS. The San Francisco-based cloud storage company cited that it had "outgrown the AWS cloud." Over the last two years, Dropbox has built its own infrastructure to prepare for the move. Today, more than 90% of its users' data is stored on Dropbox hardware and software, which leaves AWS on the side of the road. Apple will soon join Dropbox to do away with AWS workloads, as well as some other brand names making the change in the cloud vs. on-premises debate.

So why do companies move off of AWS and back to a private data center? There are several reasons.

The first thing for an enterprise to consider when comparing the AWS cloud vs. on-premises infrastructure is its ability to find a less expensive alternative.

In a cloud vs. on-premises infrastructure comparison, AWS is more expensive in some cases. An IT team must evaluate AWS usage on a case-by-case or workload-by-workload basis. Dropbox found it was cheaper to run its service on its own hardware and software, justifying the cost of migrating off AWS.

Business issues, specifically competition with AWS, can also drive customers away. In the case of Dropbox, AWS has a competing storage service. It seemed confusing to the Dropbox customer base that AWS was used for the Dropbox infrastructure, as AWS has a Dropbox-like product. This is a common theme; as AWS stretches its reach into other product lines, it steps on the markets of its own cloud customers. Dropbox grew quickly and saw a need to separate from AWS, for market confusion issues as well as cost considerations.

Control also plays into the migration decision. Technology companies and enterprises that depend too much on AWS or other clouds can become concerned that, at some point, they could lose control and become too reliant on a single vendor's products. AWS has some proprietary features, so an enterprise's technology could become dependent on those features. If AWS removes or changes one of those features, it could affect the enterprise and, potentially, its product.

The cost of an AWS egress

The first thing for an enterprise to consider when comparing the AWS cloud vs. on-premises infrastructure is its ability to find a less expensive alternative. IT professionals need to maintain the hardware and software, data center space and security and management tools, which can equal about half to two-thirds of an enterprise's IT cost. Often, the necessary technology and skills aren't factored into the business case for migration.

The real cost of migration corresponds to how much an enterprise relies on native AWS features. If it has built an on-demand product around the native capabilities of AWS, such as Simple Storage Service or Elastic Compute Cloud, then developers will have to rewrite those features using other platform analogs within the new target platform -- if comparable services even exist.

If an enterprise needs to rebuild software -- also called refactoring -- migrating off of AWS likely loses its cost incentive, even if on-premises operational costs are lower. However, if software was written to be AWS-neutral, the cost will be significantly lower and could be justifiable.

But money isn't the only motivating factor. Most big technology companies that leave AWS lack a clear business case, and market issues or control concerns are the more likely motivators.

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