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Assess VMC on AWS costs through cloud workload comparisons

Despite its benefits, VMware Cloud on AWS isn't always the most cost-effective choice for workloads. Compare pricing to EC2 instance costs to gauge which is the better option.

With VMware Cloud on AWS, an enterprise can provision the VMware suite of services directly on AWS infrastructure....

This offers a simplified migration path from a business's private data center to the public cloud. It also enables the use of existing VMware management tools, lets applications access AWS' broad cloud portfolio and can potentially lower costs compared to DIY approaches.

VMware offers support and sets pricing for the VMC on AWS service, which runs on top of bare-metal servers in AWS data centers. According to VMware, the service, which is priced comparably to an equivalent set of compute and storage capacity on AWS, can save enterprises about 40% compared to privately managed VMware infrastructure. However, enterprises need to assess the full cost of infrastructure deployment and management across the VMware and AWS ecosystems to identify the optimal ratio of services from the two providers.

Enterprises can use a variety of approaches to convert VMware images into equivalent Amazon Machine Images (AMIs) to migrate workloads to the cloud. VMware provides a variety of tools to migrate live workloads back and forth between private infrastructure and the VMC service relatively smoothly. But there are potential challenges, particularly when you need to move live applications between the VMware ecosystem and AWS.

VMC on AWS vs. EC2 pricing

To understand the VMC on AWS pricing model, compare the service's per-VM pricing with Amazon Elastic Compute Cloud (EC2) instances.

VMware estimates the total cost of ownership over three years for the VMC service is about $0.06 to $0.09 per hour based on the consolidation ratio. This compares favorably to about $0.10 to $0.17 per hour for similar capability on private infrastructure. According to VMware, these costs represent a VM that runs on two virtual CPUs (vCPUs), 8 GiB of RAM and 150 GB of storage and don't include bandwidth or IP address charges.

The closest native AWS equivalent is a t2.large instance with two vCPUs and 8 GiB of RAM. This costs $0.035 per hour when paid in advance for a three-year upfront commitment and $0.0928 per hour as an On-Demand instance. The inclusion of the equivalent 150 GB of Elastic Block Store storage adds another $0.0208 per hour. That brings the total cost for a three-year commitment to about $0.055 per hour.

You can also make an economic comparison between a basic VMC host compared to a larger EC2 instance. A host is an instance of the VMC hypervisor that runs on a single bare-metal system in the AWS data center and can host multiple VMs. An EC2 instance is a single VM that runs on top of AWS infrastructure, though it is technically possible to spin up multiple VMs on an EC2 instance using third-party tools.

In this case, the VMC host comes with two CPUs, 36 cores, 512 GiB of RAM and 14.3 TB of solid-state drive (SSD) storage. This service includes 72 hyper-threads, which means each core can simulate two separate CPUs. This costs $4.16 per hour with a three-year commitment, $5.93 per hour with a one-year commitment and $8.37 per hour on demand.

Many workloads don't easily separate across threads, so it can be tricky to directly compare AWS vCPUs to threads. AWS does, however, have a few instance sizes that come close to the VMC host in terms of vCPUs or RAM, and these are a little cheaper. The m4.16xlarge includes 64 vCPUs and 256 GiB of RAM and costs $1.203 per hour with a three-year commitment and $3.2 per hour on demand. The r4.16xlarge costs $1.6 per hour for a three-year commitment and provides 64 vCPUs and 488 GiB of RAM.

Both EC2 options would need an additional 14.3 TB of storage to match the VMC host equivalent. That storage cost adds $1.98 per hour, which brings the total to $3.18 per hour for the m4.16xlarge and $3.58 per hour for the r4.16xlarge. An x1.16xlarge instance with 64 vCPUs, 976 GiB of RAM and 1,920 GB of SSD storage costs $1.1866 with a three-year upfront commitment. But those EC2 options come with considerably less storage than the basic VMC service.

At a raw infrastructure level, enterprises might be able to save money if they migrate applications from the VMC on AWS service into AMIs that run on larger EC2 instances. The relative economics of the various approaches gets messier, however, when organizations want to migrate a mix of live and dynamic apps between infrastructures. VMware attempts to bridge this gap with a tool called VMware vRealize Business for Cloud that provides cloud cost analysis and manages application deployments to reduce costs.

In the short term, most enterprises will find it easier and more cost-effective to migrate existing VMware infrastructure to VMC on AWS. But many enterprises might save money over the long term if they convert these workloads into AMI-based apps that run on AWS infrastructure. There is, however, complexity and risk associated with this transition, and you'll need to train ops teams to manage this hybrid infrastructure.

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