This recommended configuration is designed around a building block approach with a multi-copy high availability design using a database availability group (DAG). The number of servers per DAG is a flexible design decision that customers can make (up to sixteen servers per DAG based on an Exchange Server limit). This recommended configuration uses a total of five multi-role servers, with three in the primary location and two in the secondary location. The primary datacenter is designed for a normal load of 1500 users per server under normal operations and 2250 users per server under failover of one server per DAG. The secondary datacenter is designed for 2250 users per server under failover. Complete server specifications are given in this document.

This document will focus on the 3 node configuration of HP ProLiant SL4540 Gen8. It consists of up to three compute nodes and a total of forty-five (45) large form factor (LFF) 3.5″ hard disk drives (HDD) in the chassis. The HP ProLiant SL4540 is a dual socket Gen8 server, with a choice of five different Intel® Xeon® processors, up to 192GB of memory and one PCIe slot for expansion per node. Every compute node also has its own dedicated networking ports.

Also shown is an alternate design using disks without RAID1 protection, with two Exchange copies in both the primary datacenter and the secondary datacenter, which would make it possible to use identical server configurations (CPU, memory and database layout). Since the database volumes are not protected by RAID, a single disk failure will require failover to the second Exchange copy. This design supports slightly more users and larger mailboxes due to this different architecture, but does require an additional mailbox server per DAG in the secondary or DR location.

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