VMware VCA 1V0-701 – VMware Certified Associate 6 (Retired) Part 3

21. High Availability

In this video, we’ll learn about Vsphere high Availability and how it can be used to protect our virtual machines from an ESXi host failure. So the purpose of High Availability is to protect our virtual machines from failures, but it does not provide 100% uptime. Ha is going to involve virtual machines re booting. It’s going to involve virtual machines potentially being down for a little while. If something like an ESXi host failure occurs, there is going to be an outage associated with that. What Ha does is essentially, if an ESXi host fails, all of the virtual machines running on that host will fail.

But after the fact, after that failure occurs, high Availability will start rebooting those virtual machines on different hosts within that cluster. You can protect your virtual machine from failures at the host level or you can even protect your virtual machines from virtual machine level failures with High Availability. So it can actually monitor the status of VMware tools in your virtual machines. And if VMware tool stops responding, that virtual machine can be rebooted right on the same host.

So Ha can protect you from failures at either the host or virtual machine level. And we can use things like Admission Control to ensure that we have enough spare capacity. So for example, if you have a cluster of four hosts and one of those hosts fails, we need to make sure that the surviving hosts have enough spare memory and CPU capacity to acceptably run all of the virtual machines that used to be running on that host that has now failed. That’s what we’ll use Admission Control for, is to guarantee that we have spare available capacity.

And one final point about Ha, it does not utilize V Motion. Don’t confuse Ha with DRS or with V motion. High Availability does not utilize V Motion in any way because V Motion is used for running virtual machines, virtual machines that are up with High Availability. If a host fails, my virtual machines are down. So let’s take a look at how High Availability works. Here you can see I have a VM called VM One and my VM is running on host ESXi One. And so I’ve got this VM running and right now everything is fine. My VM is working. It’s running on host one.

And my VM also has access to all of its files that are down here on shared storage. And by the way, shared storage is required for Ha. So I have to have some sort of shared storage system that all of my hosts in the cluster have access to. So I’ve got shared storage. I’ve got VM One running on ESXi One and then something happens, something goes wrong and ESXi One fails. So now my host that the VM One was running on is down and my VM can’t run if the host is down. So VM One fails right along with that host. So there’s going to be some downtime for this virtual machine and every other VM that was running on that host.

And what’s going to happen now is the virtual machine’s files are still intact. The VM’s running state or live state may have been affected, but there’s still a set of files for this virtual machine that are intact that exist on shared storage, and those files can be used to now boot up another instance of that virtual machine on some other ESXi host. And that’s how high availability works. When host one fails, host two or three or four, one of them is going to be a master host.

That host is going to recognize that, hey, host one is down. Let’s take all the VMs that were running on that host, we’ll leverage their files, which are still intact, and we’ll start booting up all those VMs on the surviving hosts within that cluster. So now we’re just going to take a very brief look at the architecture of High Availability at a pretty high level here.

And here we see VM kernel ports running on every host in my cluster, and those VM kernel ports are marked for management traffic. And so what High Availability is going to do is once we go ahead and we create our cluster in Vcenter, we go ahead and enable High Availability on this cluster. Then at that point, what will happen is once High Availability is enabled, an election will take place, and one of these hosts in the cluster will take on the role of master. Every other host in that cluster will take on the role of slave. The other thing that will happen when we enable High Availability is the fault domain Manager, or FDM, will start running on each of these hosts, and the fault domain Manager is basically responsible for these hosts communicating with each other. So the master host will be constantly sending heartbeats to all of the slaves. All of the slaves will constantly be sending heartbeats to the master. Basically, this allows the master to know, hey, if any of the slaves are down, the master will know, or if the master itself goes down, all of the slaves will know. Master sends heartbeats to the slaves, slaves send heartbeats to the master.

And this allows our cluster to detect failures. So if we have a slave host that all of a sudden goes down, it’s going to stop sending heartbeats to the master. The master can determine that, and it’ll do a couple of tricks to verify that that’s actually the case that the host is truly down, at which point those VMs that are affected can start booting up on other hosts. Okay, so from the perspective of the VMware certified associate exam, what you need to know is that High Availability provides a reliability mechanism. If a host fails, those VMs are going to restart on other ESXi hosts, but there’s going to be some downtime associated with that. And really the ideal way to configure this is to enable both High Availability and DRS on your cluster. H Eight does not use V motion, though, and we took a little brief look at the architecture.

How the master sends heartbeats to the slaves, the slaves send heartbeats to the master. And that’s how we determine if a host has failed. And the component that actually runs in the host that handles all of this heart beating and the communication between hosts. It’s called the fault.

22. vSphere Data Protection

In this video, I’ll explain the basics of Vsphere Data Protection and how it can be used to backup virtual machines. And that’s what Vsphere data protection is. It’s a backup solution specifically designed for VMware Vsphere environments that you can use to back up your virtual machines. You manage it completely using the for web client, so it uses all of the same management tools that your Visa environment already leverages. You do have to deploy a special virtual machine called Visa Data Protection Appliance, and it’s an incremental backup solution. Meaning once you create a full backup, only changed blocks are copied with each additional backup.

So the goal there is to have the amount of work required for each backup job is minimized, because only changed blocks need to be copied to the backup location. It provides virtual machine level protection and file level protection as well. And it even includes application aware backups for SQL, SharePoint and Exchange if you install an in Guest Agent. So just a couple of quick specifics about the virtual appliance, and we’re not going to really focus a lot on this, because for the VMware certified Associate, you really just need to know what the feature is for. But basically you’ll have a pre configured, pre built virtual appliance. You can use up to 20 of these per V Center instance, and it’s very easy to roll out.

Each virtual appliance requires four gigs of memory and four virtual CPUs. And so once you’ve got these For Data Protection completely rolled out and configured, you can start creating backup jobs. So you’ll basically choose the virtual machine or the container object, like a resource pool or a host that you want a backup. And you’ll set up your backup jobs. You’ll schedule the frequency of the backup job, you’ll choose how long to retain those backups for, and you can even configure the replication of that backup job to provide additional protection. And here’s a little screenshot that shows the different retention policies that you can identify. So for example, you may choose to keep one daily copy of your backups for 30 days. So we’ll retain 30 daily backups, we’ll retain one backup per week for twelve weeks, we’ll retain six monthly backups, so we can go back up to six months. And we’ll even retain one backup per year to have one annual backup per year for two years. So we could technically go back as far as two years if we really needed to.

And we can even do application consistent backups as well. For things like SQL, SharePoint and Exchange, this does require some Agent software installed in those virtual machines. It does support clustered SQL servers and exchange database availability groups. And you can even install the Vsphere Data Protection Agent on physical SQL and Exchange servers as well. And you can also do File Level Restores. Again, it requires the client to be installed in the Guest operating system, but you can even provide a self service client to your users to allow them to perform their own restores.

So you can restore individual files and folders without restoring the entire virtual machine and you can restore those files and folders to the original location or to a new location. So for the exam, what you really need to know is Vsphere data protection comes bundled with Vsphere. It’s included free of charge and it’s backup and recovery solution for Vsphere virtual machines that is managed using the Vsphere web client. We do have to deploy a pre built virtual appliance and it is an incremental backup solution. So only changed blocks are backed up and that data that’s stored is actually deduplicated as well to save space.