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Let's talk about some considerations for migrating on-premises compute resources into the cloud. In the data center, you have virtual machines. It's often possible to migrate a virtual machine directly to the cloud, but the better approach is usually to create a new virtual machine in the cloud and configure it from scratch. One reason for this is that a virtual machine running in your data center will have drivers and other software specific to the virtualization platform that you're using, which will undoubtedly be different than what the cloud provider is using. Performing a “lift and shift” migration to the cloud is asking for trouble.

The sizing of virtual machines—processor power, memory, and storage—should mirror that of your data center VMs. VMs in the cloud are fundamentally no different than the VMs in your data center. There is no “cloud magic” that makes cloud-based VMs more resource efficient. For example, an application that requires 16 GB of memory in the data center will require just as much memory when it's running in the cloud. Make sure that there is ample input/output (I/O) and low latency for storage access, and that there is enough processing and memory allocated to ensure the proper level of performance expected.

One final word on migrating machines to the cloud. Prior to machine virtualization, each physical server ran a single operating system on bare metal. This often meant that one server could host only a handful of applications. Nowadays, machine virtualization is the norm, both in the data center and in the cloud. However, you may occasionally run across an old application that for whatever reason has to run on a bare-metal server. Such applications generally aren't good candidates for moving to the cloud. If you're not sure, you can sometimes smoke out such legacy applications by looking for servers that have been exempted from operating system updates.