How to Setup HA for RHV-M pt2

Hi folks, I’m finally getting around to the high availability for RHV-M (hosted engine) walk through demo that I promised. The truth is that due to unforeseen circumstances, I had to go to “plan b”. The end result is still the same, and the workflows are almost identical, but the “in betweens” are just a bit different.

Allow me to illuminate..

So when I last left off, I was explaining the virtues of both the lightweight virtualization host (RHVH) as well as the hosted engine configuration for use as a means of providing high availability for RHV-M, the management piece for RHV. Hosted engine can support either (not both at the same time) RHVH or RHEL hosts as the hypervisor nodes.. While I really wanted to show you how get things up and running with RHVH first, I’m going to show you the “RHEL way” first. I’ll come back around the RHVH, I promise.

The workflow for getting things up and ready is very similar when comparing RHVH and RHEL – hosts, networks, and storage all get setup. DNS (forward and reverse, FQDN for hosts and RHV-M) is configured. Subscriptions are set and hosts are updated. The biggest differences are that in the RHVH hosted engine configuration, we launch from “Cockpit”, where in RHEL we launch from command line and that RHEL doesn’t use LVM thinpools. Both configurations utilize the RHV-M appliance.

Here’s the actual workflow for setting up RHEL and RHV-M for hosted engine:

  1. Have your physical hosts, storage, and networks ready
  2. Have your DNS, NTP, and any other services (PXE, RHN, etc) ready
  3. Deploy RHEL 7.2 on 1 host – be sure to have at least 60GB of space in “/var”
  4. Subscribe the host to Red Hat CDN and the necessary software channels
  5. Update the RHEL 7.2 host, then reboot if the kernel has been updated
  6. Install the “ovirt-hosted-engine-setup”, “rhevm-appliance”, and “screen” packages
  7. Run the screen command (if the network disconnects for any reason including as part of the deployment, using “screen” will be your best friend.. you won’t have to start over..)
  8. Launch the hosted engine deployment command and follow the prompts
  9. Log into the newly deployed hosted engine (RHV-M)
  10. Configure a separate storage domain for VMs so that the hosted engine components are recognized within RHV-M
  11. Add an additional RHEL host to the configuration (next post)
  12. Test failover (next post)

Let’s check out the workflow in the demo.. it’s straightforward. My environment is quite slow, so I’ve sped things up. It should move fairly quickly in a “real” environment..

Best viewed in full screen:

So that’s how we deploy hosted engine using RHEL hosts. Again, using RHVH is very similar. If you’ve seen my earlier posts, you know that deploying RHVH is slightly different as compared to deploying RHEL and as I said earlier in this article, we’ll be using “Cockpit” to deploy the engine component when we get back around to the RHVH deployment.

However, the prompts that come up during the install are the same because the RHV-M appliance is the same. So is the HA mechanism… it’s really just a matter of lightweight or full host.

I’ll come back next post with how to add the second RHEL hosted so that RHV-M has a place to failover/failback as well as how to test and maintain the hosted engine environment. And I will come back around to show you how to setup hosted engine using RHVH too.

Hope this helps,

Captain KVM

 

 

Agree? Disagree? Something to add to the conversation?