VMware HCX

VMware NSX Hybrid Connect, alternatively known as VMware Hybrid Cloud Extension (HCX) is a technology that delivers secure and seamless app mobility and infrastructure hybridity across vSphere 5.0+ versions, on-premises and in the cloud. If you want to install HCX then do refer to below document published at Vmware portal
https://docs.vmware.com/en/VMware-NSX-Hybrid-Connect/3.5.1/user-guide/GUID-A26BFB16-FA94-426F-8E18-15BAD4BF840E.html

The architecture for HCX is already well explained at VMware websites. I would like to discuss some points that are not very clear in first glance.

LICENSE: As of now there is no À la carte license for HCX. It comes bundles with VMC on AWS solution or it can be used with NSX Enterprise license. So in a nutshell it means we need to have NSX at target site in order to use HCX solution.

HCX is not just a migration tool: It can also be used for long term and some customer have kept it deployed for over a year. In such use cases, customer move their workload into public cloud as demand increases and move it back on-prem as load decreases.

Throughput: When migrating workload from one cloud to another, what actually happens is that HCX will create a copy of VM and its data on the target site. Either live or at some scheduled window we can cut over the VM from source site to target site. But if the VM is hugh like 600GB, and if there are multiple such VMs, the how much time can it take to achieve such migrations? The answer is not very simple. There are multiple items that need to be factored in this.

• The first is the minimum bandwidth link between source and target site which will act as choke point.
• Second is the maximum iops achieved in source and target SAN/datastores.
• Third is how many concurrent VM migrations are in progress and if all source VMs are spread across hosts and spread across datastores to achieve maximum throughout. HCX uses multiple IPsec tunnels between source and target site with each tunnel having a limited throughput close to 1Gbps. A single VM migration will use only one tunnel. So at any instance of time throughput of a single VM migration is limited to only one tunnel. Use of multiple VM migration means multiple tunnels are used and aggregate throughput increases. Also, those multiple VMs should be spread across different host in source site and different datastores to achieve best result.
• CPU availability on host where HCX CGW appliance is present.