Exchange 2013 Fail-over Design
In this blog-post we will discuss an standard design that will be robust and will provide ability to load-balance and fail-over without need of an Hardware Load Balancer by having Multiple Host A entries in DNS.
Hardware and Software Requirements
Windows 2012 R2
Active Directory Services
Active Directory Domain Controller Server
-Server or Virtual Machine with 8GB RAM and 100GB system Partition with at least 20GB for Backups of System State.
Additional Domain Controller
-Server or Virtual Machine with 4GB Ram and 100GB System partition.
Exchange Client Access Servers
Theses Servers will be used to serve clients, which will include, Exchange Active Sync, POP, IMAP, Outlook Anywhere, Mobile clients. will be load balanced using DNS.
-Two Server or Virtual Machine with at least 16GB of RAM and 100 GB System Partition and Exchange CAS.
Exchange Mailbox Role Server
Theses server will host mailboxes for users and will be using Exchange DAG (Data Availability Group) to provide redundancy for the exchange organization.
-Two Servers or virtual machines with at-least 24GB RAM. 100 GB system Partition, 200 GB data partition on preferably SAN or local Disk. Data partition can be increased in-case of more storage requirements.
Exchange Witness Servers
We need witness server for exchange data availability Group (DAG) which is used as quorum to the cluster, we can use fail-over cluster of witness server to provide redundancy
-Two Server or Virtual machines with at-least 4 GB RAM and 100 GB System Partition.
Following is sample configurations with assumed IP.
Mail domain :
Priority : 10