Some Thoughts on VMware Cloud on AWS Stretched Clusters

Companies are considering a variety of migration strategies as they are looking to leverage the cloud. For VMware Cloud on AWS (VMC) migration is one of the key use cases that VMware have promoted (alongside Disaster Recovery). A key benefit touted by VMware for their offering is the ability to re-host applications without having to re-platform or re-architect, however, this is not without caveats when it comes to availability and resiliency.

For a customer migrating to the cloud, delivering the right level of resiliency and availability is a key concern. On AWS the Availability Zone is a key building block for designing available architectures. For customers who are willing to re-architect their application, designing the application to ensure resiliency in the face of an AZ loss is critical, as well as ensuring customers are eligible for AWS SLA credits in the event of an EC2 outage! But what options are available for delivering multi-AZ availability when pursuing a re-host migration strategy?

For VMware Cloud on AWS, delivering this re-host capability this is also one of the most significant limitations with what is currently available. When customers provisioned a new SDDC it could only be placed within a single Availability Zone (AZ). The combination of vSphere HA, vSAN’s erasure coding, and VMC’s auto-remediation of failed hosts ensured that failures of the individual bare metal EC2 instances could be handled well. However, there remained an issue of protecting against failures of entire Availability Zones.

With the unveiling of a technology preview of their new stretched clustering capability, VMware is presenting a differentiated offering. Stretched networking, by NSX, and stretched storage, from vSAN, combine with vSphere’s HA to deliver a platform that delivers resiliency against AZ failure, without having to re-architect or re-platform your application to take advantage of multiple Availability Zones. On the vSAN side, the increased costs of mirroring the storage are now offset by the introduction of deduplication and compression support. More details were shared during VMware’s recent Cloud Briefing event and I also spoke about VMware’s plans here during my VMC storage deep-dive session at VMworld.

It will be interesting to see how VMware’s customers evaluate this new offering when it moves out of tech preview status and into General Availability.