Stretched Clusters provide the ability to protect an SDDC running in VMware Cloud on AWS from an Availability Zone failure. If you would like to know more about the Stretched Clusters capability, sometimes referred to as Multi AZ SDDCs in VMW on AWS, make sure you read this article by Emad Younis, this post by Frank Denneman and this article by Glenn Sizemore. In addition, as announced in December 2019, there is a 95% discount on the cross-AZ traffic between the AZs.
Just like a standard vSAN cluster, storage consumption in a Stretched Cluster is managed using storage policies.
When we assist customers in designing a new VMware Cloud on AWS SDDC the question of Layer 2 extension comes up frequently. The reasons to extend on-prem networks are unique to each environment and can be a temporary state during migration or a long term strategy to ease scalability and bursting to the cloud.
VMW on AWS provides two options for extending an on-prem network to the SDDC - HCX Network Extension (NE) and Layer 2 VPN. While both solutions provide the same functionality they are different in several aspects. I won’t go into a detailed comparison in this post, but most users, especially if they are not very familiar with networking, will find that HCX NE is easier to configure and scale.