Finally Exchange 2013 server role requirements calculator
The calculator has been improved in several ways for high availability architectures:
- You can now specify the Witness Server location, either primary, secondary, or tertiary datacenter.
- The calculator allows you to simulate WAN failures, so that you can see how the databases are distributed during the worst failure mode.
- The calculator allows you to name servers and define a database prefix which are then used in the deployment scripts.
- The distribution algorithm supports single datacenter HA deployments, Active/Passive deployments, and Active/Active deployments.
- The calculator includes a PowerShell script to automate DAG creation.
- In the event you are deploying your high availability architecture with direct attached storage, you can now specify the maximum number of database volumes each server will support. For example, if you are deploying a server architecture that can support 24 disks, you can specify a maximum support of 20 database volumes (leaving 2 disks for system, 1 disk for Restore Volume, and 1 disks as a spare for AutoReseed).
You can read the full article from here
You can download the calculator from here