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RP4VM failover testing network

18 May

Updated this article after Peter’s comments and my own testing

During failover of an RP4VM consistency group (CG), you have a few choices of selecting the test network to failover your VMs in. Why is this necessary?

RP4VM_Network

First, we need to understand that a failover action is not immediate and it comes in two stages. First is image access and then the actual failover. Image access allow you to bring up the replicated instance and test them before you decide on failing over, which makes the replicated copy the master copy. If testing during image access fails, you can always cancel the failover without any impact.

In steady state, the replicated image although powered on is sort of a container. During image access this container is reconfigure as the actual VM and booted up. However, the master VM is not shutdown during image access by RP4VM, it is only shutdown (converted to a container) when you actually confirm the failover.  In this case, to prevent IP conflicts in a stretched network, you either shutdown the master VM before initiating image access or you specify an isolated network to bring up the replicated VMs.

The last two options, i.e. Use my dedicated network and skip this step, can be a bit confusing for some of us, plus the documentation isn’t really clear on what actually happens.

If you had not shutdown the master VM when initiating an image access AND you are failing over on a stretched network, you may want to choose the first 3 options of isolating the VMs on the failover site.

If you had shutdown the master VM, then you can select the last two options. The option “Use my dedicated network” allows you to select you choice network to test your VMs. When the VMs are powered on during image access, they will be configured with the network that you chose. This is only a temporary arrangement. During actual failover, the network on the replicated VMs will revert to their originally configured network.

During a DR situation in which there is either network isolation OR you had shutdown the master VMs, you should just select “Skip this step”. On image access, the replicated VMs will just be boot up in whatever network they are configured in.

 

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2 Comments

Posted by on May 18, 2017 in Cloud, vmware

 

Tags: , , ,

2 responses to “RP4VM failover testing network

  1. Peter Ooi

    June 3, 2017 at 2:59 am

    Hi Kelvin, what you are depicting here is the network the VM would be inserted into during Image Access and NOT the actual failover network. Think of it like a test bubble network in SRM where you have the ability to choose what network to “test” your VM. After image access is complete, when you click failover, it will choose the network that the shadow VM was originally assigned to as your failover network.

     
    • Kelvin Wong

      June 3, 2017 at 2:08 pm

      Hi Peter,

      Thanks for the reply and it makes sense. We didn’t have time to test this out, will do so and update.

       

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