Google Inc. reignited the cloud price wars last week at its Next cloud conference when it announced “committed use discounts” for customers that commit to a one- or three-year contract to use its virtual computers.

A quick study by RightScale Inc. had found Google’s pricing offers substantial savings versus Amazon Web Services’ own Reserved Instances offer for its compute service, which follows a similar concept. RightScale’s study also said Google’s discounts are more flexible than Amazon’s because users don’t have to commit to a specific virtual machine instance type. Instead, the company just estimates the aggregated virtual compute and/or memory customers will use.

Never one to be outdone, Amazon.com Inc.’s cloud operation has now responded in kind with a new offer, “Instance Size Flexibility” for its Reserved Instances, that allows customers to change the virtual machine type they’ve reserved.

Amazon offers customers a variety of different virtual machines in various sizes. Now, with the Instance Size Flexibility offer, Amazon is allowing customers to switch from one size of virtual machine to another as long as it’s one within the same family of instances. In addition, Amazon allows customers to sign up for Convertible Reserved Instances, which enables them to switch between the VM types it offers, though the discount isn’t as big.

For now, the offer is available only to Linux/Unix Regional Reserved Instances, so customers who are running alternative software such as Windows Server won’t be able to take advantage of the greater flexibility.

Still, it’s interesting that Amazon felt it needed to respond to Google’s move in an attempt to reinforce the idea that its cloud is one of the most flexible when it comes to pricing.

Image: AWS