Jovan Popovic has a couple of posts covering configuration for Azure SQL Managed Instances. First, he looks at how to configure tempdb:
One limitation in the current public preview is that tempdb don’t preserves custom settings after fail-over happens. If you add new files to tempdb or change file size, these settings will not be preserved after fail-over, and original tempdb will be re-created on the new instance. This is a temporary limitation and it will be fixed during public preview.
However, since Managed Instance supports SQL Agent, and SQL Agent can be configured to execute some script when SQL Agent start, you can workaround this issue and create a SQL Agent job that will pre-configure your tempdb.
SQL Agent will start whenever Managed Instance fail-over and the job that contains script above can increase tempdb size before you start running your workload on the new instance.
Managed Instance is your dedicated resource that is placed in Azure Virtual network with assigned private IP address. Before you create Managed Instance, you need to create Azure Virtual network using Azure portal, PowerShell, or Azure CLI.
If you are using Azure portal, make sure that you use Resource Manager ake sure that Service Endpoints option is Disabled in Creating Virtual Network Blade (this is default option so don’t change it).
If you want to have only one subnet in your Virtual Network (Virtual Network blade will enable you to define first subnet called default), you need to know that Managed Instance subnet can have between 16 and 256 addresses. Therefore, use subnet masks /28 to /24 when defining your subnet IP ranges for default subnet. If you know how many instances you will have make sure that you have at least 2 addresses per instance + 5 system addresses in the default subnet.
Both posts are useful if you’re interested in getting started with a managed instance.