What if Application Down in Azure Cloud of Particular Rack in Data Center Under Planned Maintenance || Availability Sets

#Use Case

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Customer Want to Move their On-premises Application onto Azure subscription.The aplication will be Hosted on Several Azure Virtual Machines.They Need to make changes so that the Application will always be running on at least four Virtual Machines During a Planned Azure Maintenance period

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Solution

Availability set

Ensuring The availability Set during the Creation of Virtual Machines can help the Application will always running on virtual machines with SLA of 99.95%

As per Customer requirements ,Five Update Domains required for the Application that will be running on Atleast Four Virtual machines During **Planned Maintanance Period**

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Steps to Implement Availability Set

1. Login to the Azure Portal and select “+ Create a resource”.

2. 
   
   

3. In the Azure Market Place, search for Availability Set.

4. From the search results, select “Availability Set”. and In the Availability Set panel, select create.

5. In the create availability set panel, define the parameters.
   Name: Enter the name of the availability set.
   Subscription: Select the subscription.
   Resource group: Either create a new one or select an existing one based on your requirement.
   Location: Select the location.
   

   Fault domains: Select the number of fault domains, by default it is two but for specific Azure regions we can select up to three fault domains.

   Update domains: Select the number of update domains, by default it is five but we go up to 20 update domains in each availability sets.

   Use managed disks: Select Yes (by default) if you would like to use managed disk for all the VMs that will be create in this availability set otherwise “No”.

6. Click on Review+Create

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1. Now Create Four virtual Machines by Choosing Avilability set with Five Update Domains
2. 

**Note**

Once we created an availability set, we will not able to modify it and the same concept applies to VM as well. If we have created a VM as part of the availability set then we can’t come out or change the availability set until we delete and recreate it.