Exchange Server 2013 administration overview : Exchange Server 2013 and your hardware

Knowledgeable Exchange administrators

Strong architecture

Appropriate hardware

Memory . The minimum random access memory (RAM) is 8 gigabytes (GB) for servers with both the Mailbox Server and Client Access Server roles, 8 GB for Mailbox servers, and 4 GB for Client Access servers. In most cases, you’ll want to have at least twice the recommended minimum amount of memory. The primary reason for this is performance. Most of the Mailbox server installations I run use 16 GB of RAM as a starting point, even in small installations. In multiple Exchange server installations, the Mailbox server should have at least 2 GB of RAM plus 5 megabytes (MB) of RAM per mailbox (with a minimum of 8 GB regardless). For all Exchange server configurations, the paging file should be at least equal to the amount of RAM in the server plus 10 MB.

CPU . Exchange Server 2013 runs on the x64 family of processors from AMD and Intel, including AMD64 and Intel 64. You can achieve significant performance improvements with a high level of processor cache. Look closely at the L1, L2, and L3 cache options available—a higher cache can yield much better performance overall. Look also at the speed of the front-side bus. The faster the bus speed, the faster the CPU can access memory.

Exchange Server 2013 runs only on 64-bit hardware. The primary advantages of 64-bit processors over 32-bit processors are related to memory limitations and data access. Because 64-bit processors can address more than 4 GB of memory at a time without physical address extension, they can store greater amounts of data in main memory, providing direct access to and faster processing of data. In addition, 64-bit processors can process data and execute instruction sets that are twice as large as 32-bit processors. Accessing 64 bits of data (versus 32 bits) offers a significant advantage when processing complex calculations that require a high level of precision.

SMP . Exchange Server 2013 supports symmetric multiprocessors, and you’ll see significant performance improvements if you use multiple CPUs—not just multiple cores in a single CPU. Although the clock speed of the CPU is important, so are the number of logical processor cores and the number of threads that can be simultaneously processed. That said, if Exchange Server is supporting a small organization with a single domain, one CPU with multiple cores may be enough. If the server supports a medium or large organization or handles mail for multiple domains, you will want to consider adding processors. When it comes to processor cores, I prefer two multicore processors to a single processor with the same number of cores, given current price and performance tradeoffs. An alternative is to distribute the workload across different servers based on where you locate resources.

Disk drives . The data storage capacity you need depends entirely on the number and size of the data that will pass through, be journaled on, or stored on the Exchange server. You need enough disk space to store all data and logs, plus workspace, system files, and virtual memory. Input/output (I/O) throughput is just as important as drive capacity. Rather than use one large drive, you should use several drives, which allows you to configure fault tolerance with RAID. As part of your hardware planning, it’s important to point out that Exchange 2013 supports multiple databases on the same volume, allowing you to have a mix of active and passive copies on a single volume. Keep in mind, however, the input/output per second (IOPS) capabilities for the underlying physical disks. Also note that even if you’ve been assigned multiple logical unit numbers (LUNs) for use from storage these different LUNs may be spread over the same physical disks.

Data protection . You can add protection against unexpected drive failures by using redundant storage. For the boot and system disks, use RAID 1 on internal drives. However, because of the new high-availability features, you might not want to use software RAID for Exchange data and logs. You also might not want to use expensive disk storage systems either. Instead, deploy multiple Exchange servers with the required server roles.

If you decide to use software-based redundant storage, you can use disk striping without parity or disk striping with parity for data volumes. Disk striping without parity offers good read/write performance, but a failed drive means that Exchange Server can’t continue operation on an affected database until the drive is replaced and data is restored from backup. Disk mirroring creates duplicate copies of data on separate drives; you can rebuild a mirrored unit to restore full operations and can continue operations if one of the drives fails. Disk striping with parity offers good protection against single drive failure, but it has poor write performance. For best performance and fault tolerance, RAID 10 (also referred to as RAID 0 + 1), which consists of disk mirroring and disk striping without parity, is also an option.

Uninterruptible power supply . Exchange Server 2013 is designed to maintain database integrity at all times and can recover information using transaction logs. This doesn’t protect the server hardware, however, from sudden power loss or power spikes, both of which can seriously damage hardware. To prevent this, connect your server to an uninterruptible power supply (UPS). A UPS gives you time to shut down the server or servers properly in the event of a power outage. Proper shutdown is especially important on servers using write-back caching controllers. These controllers temporarily store data in cache. Without proper shutdown, this data can be lost before it is written to disk. To prevent data loss, write-back caching controllers typically have batteries that help ensure that changes can be written to disk after the system comes back online.