Cloud Migration Series: Part 1 – Getting Started with Hybrid Cloud Migration

The hybrid cloud conversation, and subsequently cloud migration, is a hot topic amongst customers – some for it, some against it, and some conflicted. Not too long ago the hybrid cloud model was complicated and brought up feelings of uncertainty, and doubt. Questions about re-architecting applications and re-educating staff, new tools and best practices, as well as security were (and still are) at the forefront of everyone’s minds. Of course, it’s technology, and nothing is ever easy; but with VMware Cloud on AWS we aim to ease that pain, confusion, and doubt associated with the native cloud model. They hybrid cloud model is quickly becoming a way of life, almost mandatory, in a variety of industries. But even if it isn’t mandatory for your industry or company, why shouldn’t you reap the benefits of it?

There are a number of reasons why an organization may want to move their virtual machines into the cloud. Scalability and elasticity allow you to quickly grow your cluster(s) for new projects or greater demand without having to go through a full procurement and deployment process. Physical data center limitations such as floor space, cabinet space, power, and cooling could stifle an organization’s ability to scale infrastructure and applications. Perhaps you need the ability to place applications closer to a particular department or user base in different countries around the world. Maybe none of these apply, but your CIO simply wants to implement a cloud first initiative.

The ability to migrate virtual machines into the cloud solves these problems and many more. Migrating virtual machines to VMware Cloud on AWS vs native cloud comes with a great deal of benefits. First, the stress and cost of re-factoring goes right out the window, after all, you’re simply moving a vSphere virtual machine to another vSphere environment. Second, there’s no need to re-educate or re-train staff. There’s no learning curve because the software, tools, and processes largely remain the same. In fact, you might benefit more with a rich feature set and tools that will help you understand your workloads better, minimize downtime, and potentially increase SLAs for mission critical applications.

In Part 1 of this series we will dive into the basics, to get you started moving virtual machines into VMware Cloud on AWS. Throughout the series we’ll introduce VMware HCX and dive into the components, migration methods, and details surrounding the Service Mesh. Finally, we’ll wrap up the series with some best practices and considerations around planning your application migrations for success.


Bridging On-Premises with the Cloud

Hybrid Linked Mode (HLM) allows you to link your VMware Cloud on AWS vCenter Server instance with your on-premises Single Sign-On domain. Similar to Enhanced Linked Mode (ELM), this will provide operational consistency allowing you to view and manage both vCenter inventories within a single pane of glass utilizing your on-premises LDAP or AD credentials. HLM also allows you to share tags and categories, as well as migrate virtual machine between vCenter Server instances.

There are two options for configuring HLM. The first, and preferred, option is to deploy the vCenter Cloud Gateway appliance on-premises. This appliance sits in between both vCenter Servers and maintains the link between them. Logging into either vCenter will only show you that vCenter’s local inventory but logging directly into the vCenter Cloud Gateway UI will allow you to see both inventories and allow you to kick off migrations. The appliance even updates itself automatically!

The second option is to link your cloud SDDC vCenter back to your on-premises data center, creating a one-way trust, and adding your Active Directory server an identity source. With this option, you can obtain a single pane of glass only by logging into your Cloud vCenter Server instance.


Right-Click, Migrate!


It should be noted that HLM is NOT a requirement for migrating virtual machines by CLI or API, only for migrations that would be initiated from the vSphere Client.

For more information about the Hybrid Linked Mode requirements and how to deploy the vCenter Gateway appliance, check out the product walkthrough.


Hybrid Migration

A hybrid migration is the process of moving virtual machines between an on-premises data center and the cloud. There are three primary methods of migration:

  1. Cold Migration: Move a powered-off VM from one host to another. The VM incurs downtime during the entirety of the migration process.
  2. vMotion: Move a powered-on VM from one host to another without incurring any downtime.
  3. VMware HCX: Allows various methods of migrating VMs from on-premises to the SDDC with or without downtime. Takes advantage of replication, deduplication, and compression with greater flexibility for older on-premises vSphere versions. Includes a number of additional features to easy migration.

Note: In the first part of this series we are only going to cover cold migration and vMotion. VMware HCX, which has its own subset of migration methods and will be covered in Part 2.

As stated above, migrations can be initiated via the vSphere Client once Hybrid Linked Mode (HLM) is configured. They can also be initiated via the command-line using PowerCLI or leveraging the API. Kyle Ruddy wrote a great blog post on using PowerCLI for Cross vCenter vMotion, and it applies to this scenario as well.


Hybrid Migration Requirements

Cold migration and vMotion both have prerequisites and specific configurations that need to be in place in order for them to be successful. A lot of the requirements are the same, but vMotion has some additional considerations. Both methods require the following:

  • On-premises vSphere version 6.5p03+ or 6.7u1+
  • On-premises vSphere VDS version 6.0 or higher
  • Hybrid Linked Mode configured if using the vSphere Client for migration
  • On-premises DNS needs to be able to resolve the Cloud vCenter server instance.

The firewall rules for both Cold Migration and vMotion are identical with one exception. In order to do a vMotion, you need one additional rule – to allow vMotion traffic (TCP 8000) between the on-premises vMotion VMkernel networks and the Cloud ESXi host subnet.


VMC Firewall Rules


Network connectivity between your on-premises data center and the SDDC is the major differentiator for when using these two methods. For cold migrations you can make use of AWS Direct Connect (DX), but really only need to have an IPsec VPN configured between environments. For vMotion, it is a hard requirement to have AWS Direct Connect with Private VIF and L2 VPN configured. Remember, we’re moving a live instance of a VM, there needs to be a solid connection in place for the migration to be successful. Long distance/cross-vCenter vMotion requirements apply – requiring a minimum 250 Mbps between source and destination with a max latency of 100 ms round trip. Lastly, virtual machine compatibility (hardware) needs to be at version 9 or later for vMotion.


VMC Connectivity


Once the requirements above have been met, you can migrate VMs as you see fit – whether they can afford downtime or not will determine the method you can use.

In Part 2 we dive into VMware HCX and how we can become even more flexible with our migration options.


Cloud Migration Series


Part 1: Getting Started with Hybrid Cloud Migration
Part 2: VMware HCX Overview
Part 3: The HCX Interconnect and Multi-Site Service Mesh
Part 4: Planning and Considerations




For further information on Cloud Migration or VMware Cloud on AWS, check out the valuable resources below: