You manage an on-premises, multi-tier application that has the following configuration:
- Two SQL Server 2012 databases named SQL1 and SQL2
- Two application servers named AppServerl and AppServer2 that run IIS
You plan to move your application to Azure.
You need to ensure that during an Azure update cycle or a hardware failure, the application remains available.
Which two deployment configurations should you implement? Each correct answer presents part of the solution.
A. Deploy AppServerl and AppServer2 in a single availability set.
B. Deploy all servers in a single availability set.
C. Deploy SQL1 and AppServerl in a single availability set.
D. Deploy SQL2 and AppServer2 in a single availability set.
E. Deploy SQL1 and SQL2 in a single availability set.
Explanation:
You should deploy AppServerl and AppServer2 in a single availability set.
You should deploy SQL1 and SQL2 in a single availability set.
Note: Using availability sets allows you to build in redundancy for your Azure services. By grouping related virtual machines and services (tiers) into an availability set (in this case, deploying both of your databases into an availability set), you ensure that if there is a planned or unplanned outage, your services will remain available. At the most basic level, virtual machines in an availability set are put into a different fault domain and update domain. An update domain allows virtual machines to have updates installed and then the virtual machines are rebooted together.
If you have two virtual machines in an availability set, each in its own update domain, a rebooting of one server does not bring down all of the servers in a given tier. A fault domain operates in the same manner, so if there is a physical problem with a server, rack, network, or other service, both machines are separated, and services will continue.
Incorrect Answers:
B: You should not deploy all servers in a single availability set. This will not provide the fault tolerance needed, as all machines would be rebooted (or suffer a hardware failure) together.
C: SQL1 and AppServerl provide different services, so they should not be grouped together.
D: You should not deploy SQL2 and AppServer2 in a single availability set. SQL2 and AppServer2 provide different services, so they should not be grouped together.
References: https://docs.microsoft.com/en-us/azure/virtual-machines/windows/manage-availability