Wednesday, June 6, 2018

How to deploy Highly available virtual Machines in Microsoft Azure.

If you have an concern about the hosted VM availability and the reliability then you can select this option to reduce the risk which is involve with that.

This solution is is supported through the Azure Availability set and that ensure that the VMs you deploy on Azure are distributed across multiple isolated hardware nodes in a cluster.If you are implementing this then if there is any failures with the Azure Hardware or the software then that will be impact only to the subset of the VM and the total solution will remaining without any downtime.

To configure this first you need to create your availability set and then need to add the VMs into that while crating the VMs.

There are two ways that you can create this,

* When creating the Virtual Machine under settings you can find the Availability Set selection and there itself can create.

* Create Availability Set first and then add that in to the VM while creating the Azure Virtual machine.

1. First go into the portal and search for Availability Set. Click on that.


2. Next click on ad and give the required information.


There you can see that fault domain and the update domains are listed,

Fault Domain : When you put VMs in to an availability set, Azure guarantees to spread them across Fault Domains and Update Domains. A Fault Domain (FD) is essentially a rack of servers. It consumes subsystems like network, power, cooling etc. So 2 VMs in the same availability set means Azure will provision them in to 2 different racks so that if say, the network or the power failed, only one rack would be affected.


Update Domain :  Sometimes you need to update your app, or Microsoft needs to update the host on which your VM(s) are running. Note that with IaaS VMs, Microsoft does not automatically update your VMs. You have complete control (and responsibility) over that. But say if a serious security vulnerability is identified and a patch created. It’s in Microosft’s interest to get that applied to the host underneath your VM as soon as possible. So how is that done without taking your service offline? Update Domains. It’s similar to the FD methods, only this time, instead of an accidental failure, there is a purposeful move to take down one (or more) of your servers. So to make sure your service doesn’t go offline because of an update, it will walk through your update domains one after the other.

3. Click Yes on the User Manage Disk

4. Adding Virtual machines into the Availability set

- Start creating the VM and under Settings, you can find the Availability Set.

- Click on the Availability set and the created availability set can be found there.

- Select the created availability set.


5. Same job run add the next servers also into the Availability set.

6. Go into Availability Set and verify the status


Note : The availability set can only be configured when creating a virtual machine. You must recreate the virtual machine to move it in or out of an availability set

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