Thursday, 30 August 2012

VMware vSphere Replication

Just 1 week ago I have finished building Disaster Recovery solution using vSphere Site Recovery Manager product. At this time vSphere Replication was solely part of SRM, but not of the vSphere. That's why I was a bit surprised when I saw "Introduction to vSphere Replication" as a part of "What's New in vSphere 5.1" documentation. At first sight it looked as a competitive contradiction to a current Disaster Recovery solution - SRM. But when I started to read the documentation I suddenly remembered that when I was playing around with Windows 2012 Release Preview I noticed that Microsoft included new free feature called Hyper-V Replica, which was supposed to provide Disaster Recovery functionality. Considering that it was absolutely free of charge benefit it had at least one strong advantage over VMware SRM.

So now it has gotten clear that this is just an answer to Microsoft challenge on Virtualization Market. When I went further into What's New documentation I found some other obvious evidence that VMware is striking back on Microsoft Server 2012.

Now, after I have done some reading I can see that vSphere Replication can replace SRM in small companies only. Here are the reasons:
  • Having it working in your infrastructure doesn't provide automation/orchestration of Disaster Recovery scenario. The same statement applies to Hyper-V Replica. You will need either powershell scripts or System Center Orchestrator to get automation options. 
  • Each Virtual Machines at the Recovery Site has to be powered on manually
  • You will need to reconnect each your VM to the correct network.
  • There might be necessity to Renumber IP addresses of some VMs - again, manually.
  • You will miss possibility to test your recovery plan during working hours since you cannot power on Replica VM if the original VM is still running and reachable.
  • There is no failback option in vSphere Replication. 

Well, it must be admitted that if you have all your steps of Disaster Recovery scenario well-documented and throughly tested you may deal with it just fine with probably 10 to 100 virtual machines. 
However, every single manual action significantly increases risk of human error, especially when every minute matters. Multiply all steps need to be taken by hundred/thousand VMs running in big enterprises  and you understand why it is not applicable. You can also take into the account the fact that there is not always a qualified person at the Recovery Site who can take care of all DR procedures properly.

Nevertheless, it looks like an adequate answer to Microsoft, considering that you can protect all your VMs at no cost if you own license starting from Essentials Plus Kit to Enterprise Plus Edition. An ideal solution for small companies seeking how to cut expenses on Disaster Recovery.

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1 comment:

  1. disclaimer: vmware employee

    also ran a session specifically on this at VMworld (repeating it in VMworld EMEA as well...shameless plug!) anyway content is here: