vSphere Migration Scenario #1

Introduction

I’ve been doing a lot of virtual machine migration work, both physical to virtual (P2V) and virtual to virtual (V2V) and with the recent migration work, I faced a challenging scenario and decided to share my experience.

Infrastructure

1. Two clusters in a same vCenter server:
   • Source_Cluster
   • Destination_Cluster
2. Each cluster has 4 ESXi servers
3. Storage is FC based but not shared across clusters and storage systems are different:
   • Source_Cluster uses Storage_VendorA
   • Destination_Cluster uses Storage_VendorB
4. Each cluster has it’s own dvSwitch:
   • Source_dvSwitch
   • Destination_dvSwitch
5. There are two 10GBe uplinks for all ESXi servers in Source_Cluster & Destination_Cluster
6. Different network configuration on physical interfaces:
   • LAG & LACP are enabled on the Destination_Cluster
   • Active/Active on the Source_Cluster, i.e. no LAG
7. Management & vMotion VMkernel are in different VLAN
   • VLAN 1000 for Source_Cluster
   • VLAN 2000 for Destination_Cluster
8. vMotion VMKernels are in different subnet
9. There is only one shared VLAN, VLAN 3000

Pre-requisites

The plan was to migrate virtual machines from source cluster to destination cluster with the new migration type “Change both host and datastore” (note that it’s available on web-client only).

To use this new feature, there were some pre-requisites to be met:

1. Source and destination ESXi servers must be in a same dvSwitch, with at least one uplink for both dvSwitches from both ESXi servers
2. The vMotion VMkernels for source and destination ESXi servers must be in a same subnet
3. Virtual machines must be using a portgroup that’s available on both source and destination ESXi servers
4. Storage doesn’t have to be shared
   • Storage vMotion without shared storage rely on network, i.e. vMotion network

How could we achieve this? Let’s take a look at it in depth, a figure is attached below.

The above figure represents how the clusters are setup (before migration). To allow vMotion and storage vMotion to work, firstly, a single dvSwitch must be shared across. Since the destination ESXi server is configured with LAG & LACP, it’s decided pull one uplink out from the source dvSwitch and add it to the destination dvSwitch. It will look like the following:

Next task is to put vMotion VMkernels in a same subnet and it needs to be performed for all 8 ESXi servers. Make sure you record the previous VMkernel information as they will have to be used while reverting back.

The last bit is, all virtual machines must be using a portgroup that is shared between clusters. This could be accomplished simply by using a portgroup in destination dvSwitch, please make a reference to the figure above.

There are 3 ways of doing this:

Migration Plan