Hyper V Replication and Failover

Today's Topic:
We discuss Hyper V Replication and failover and the benefits and dangers of using it. Hyper V Replication and Failover is demonstrated on Windows Server 2012 R2 with 2 servers.

The biggest issue with Hyper V Replication and Failover is the possibility of "split brain" where you accidentally initiate the replicated copy of a virtual machine while the original is still running. This may cause clients to use both machines simultaneously and the data stores will no longer remain identical. It this happens to specific types of servers it may end up being catastrophic to your infrastructure.

To use Hyper V Replication and Failover:
-It is easiest if you setup an Active Directory Domain and the both servers are members of it.
-Add Hyper V to both machines
-Enable Hyper V replication services on both machines
-Enable replication for EACH virtual machine to be replicated.
-Before doing a Failover verify the replication health

Today's Review:

Today's Questions:
"What books should I read to learn web design?"

"How do I upload files onto a Virtual Server?"

Today's Final Thoughts:
Make sure that you have laid a good foundation for accepting help before you ask for it.

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[JTCGiantz]

You are easily one of the most knowledgeable guys on YouTube. Learn so much from your videos. Whats are you currently doing job wise?

[edmaximovich]

Eli is great.   I have read the books and been in I.T. for 25 years, and still refer to his videos when I am unsure about something.  he is like having a coach at your finger tips.

[James-sclz]

Great video and thanks for sharing.

One minor thing is "must" enable incoming rule for hyper-v http or https depending on which you choose. Failing to do this will mean replication of the VM will not work.

[armlucifer]

Just discovered this channel, pretty good stuff. Easy way to get started.

You kept emphasizing not to get split brain, but did not specify how to prevent it. While I was listening to you, I thought of the following. Let me know if you think that would work. 

You can use an extra NCI to connect host servers to each other with a cross-over cables and manually set TCP/IP. This way they will always talk to each other, even if routing rules or network switches break. That will be like a "heartbeat" connection between hosts that hopefully instances will be able to read.

[keegangriffiths]

In regards to the "Compress the Data that is Transmitted over the network." (13:25) check-box.
If enabled you will save some network bandwidth at the cost additional CPU resources on the server. If disabled there will be no additional stress on the CPU but more bandwidth is required. 

[dclugay]

Last year I was puzzled by split brain, this year I learned, witnessed it in the flesh thankfully in a classroom project environment though.

[Joedarter]

Eli, "Split Brain" isn't such a big deal! Should it happen where you work the solution is very simple, you take YOUR BRAIN and SPLIT!! Should you be chained to your desk, you are screwed. My brain begins having spasms just trying to imagine that scenario. I'm a newb as far as Virtualization, but have enough experience to recognize the horror. BTW, new to your channel and am learning a great deal and reenforcing much of what I already know. Thanks for sharing your expertise.

[mohly]

Eli your way of explaining has improved a lot better through the past years.... btw what's the story behind the execution orange shirt? LOL

[paulstuffins]

Eli,

I have learned more from watching your videos, the Windows 2012 series and a few others here and there, than from any other location, including the book I purchased about Windows 2012 R2, keep up with the excellent videos!

In this video you say that the host machine running Hyper-V should be added to a Windows Domain, I want the DC to be in one of the VM's, which are replicated to an off-site location for backup purposes. Can the host be added to a DC that is running in a Guest VM and is that a good idea?

Also, you mentioned you would set up Certificate Based Auth for replication in a later video, did you manage to get around to that or not?

[elmol]

I heard that licenses of Hyper-v on Server 2012 R2 doesn't mean that you can install another full license of server as VM. It means that you have to buy the license of Windows Server. You have two instances of those two licensed VMs. once you used the two instances, you have to buy extra licenses on top of MS Server licenses for each VM.

[urcybersecurity]

Eli, thank you for this lesson. Just to be clear, failover is a manual process only, not automatic?

[jwraight]

Hi Eli,

When you say the best way to setup the replication is to use Kerberos... you say setup active directory on server 1. Do you mean setup a separate AD instance on the HOST and literally just have the 2 hosts in this AD environment just so they can use Kerberos ? Or do you mean join the two Hyper-V host servers to the AD on one of the virtual members ?

[vanvino]

Interesting! This looks like a pretty quick and slick solution to get data offsite for an included price... Onsite however I wonder how this compares to Microsoft's built in Failover Cluster. I guess this would require more storage since you are storing two copies of the VM, but it would get around the requirement of shared storage.

[ZeroTwoFour]

I don't get it, why wouldn't you make your failover server after a certain incedent, become a main server, while the failed one is fixed, and once it is fixed, it becomes a new failover, or you just sync with the data the failover server got. This process will liturally avoid the splitbrain situation.

[sam]

Nice to know that hyper-v can replicate so to be used as a virtual cluster. But good to know about lag time and not starting 2 instances out of sync issues. Curious how different is other virtualization systems level 1 i only really worked with level 2

[fenimama]

I am still waiting for years to understand How to shut down Hyper-V Fail over cluster. I need to know the sequence, best practise for shutting down VMs, physical servers. Which is first? Please HELP.

[DrewR]

Question - since cloud upload speeds can be very slow (looking at you, onedrive!), is it really worth for average users, or even businesses, replacing servers and hard drives for cloud storage and cloud backups?

[cldprince]

Thanks for the great vid. Hope you keep doing this for a long time :)

[TN_HondaDad]

how did you originally get the same VM "clones"/instances on server 2 so you can setup replication in the very beginning of your video session demo?

[TimBrownTown]

The rant about Split Brain was hilarious!