If you are replicating VMs for the first time in the Azure Migrate project, the Azure Migration Server Migration tool will automatically provide the following resources:

• Azure Service bus: The Azure Migrate Server Migration tool uses the Azure Service Bus to send replication orchestration messages to the appliance.
• Gateway storage account: Server Migration uses the gateway storage account to store state information about the VMs that are being replicated.
• Log storage account: The Azure Migrate appliance uploads replication logs for VMs to a log storage account. Then, the replication information will be applied to the replicated managed disks. 
• Key vault: The Azure Migrate appliance uses the key vault to manage connection strings for the service bus, as well as the access keys for the storage accounts that are used in replication.