Storage Area Networks in an Exchange Server Environment

What are your plans for implementing Storage Area Network (SAN) technology for your Exchange Server deployment? In my opinion, storage is one of the critical success factors for Exchange in terms of both performance and high availability. SAN technology is important for current Exchange Server 5.5 deployments, and will be essential when moving to Exchange 2000 Server (formerly code-named Platinum).

I’m not convinced that SAN technology is all that new (we all just love a new acronym from time to time). Compaq, IBM, HP, EMC, and others have been delivering many of the touted capabilities of SANs for several years. For Exchange, the most useful features include multiple host attachment, redundancy options, disk cloning, multimirroring, and snapshots. In addition, the ability to connect high-performance backup devices directly into a storage bus also benefits Exchange.

When you connect an Exchange server to a SAN, you can achieve a greater degree of manageability and flexibility. For example, because servers and storage units are all sharing a common interconnect, devices are no longer subject to the solitary ownership of just one server. Multiple Exchange servers can connect to a SAN, and you can divide the storage among them. Also, you can reassign storage throughout the SAN, making capacity growth a little more manageable. From a performance perspective, SANs provide a high degree of I/O scalability as well. Many SANs solutions can deliver 12,000 to 20,000 I/Os per second or more.

From a backup, recovery, and reliability point of view, SANs shine in an Exchange environment. The capability to clone or mirror volumes and create snapshots gives Exchange administrators and operators a few more recovery options for increasing system availability. Also, because you can connect tape libraries and other backup devices to the SAN and share them with other devices, backup and restore operations are more flexible and perform well. Clustering also wins in a SAN environment. With Microsoft Cluster Server (MSCS), shared storage is the only option. If you've attached multiple Exchange servers to a SAN, taking the next step to clustering becomes fairly simple. You might not consider clustering for Exchange Server 5.5 to be a viable option, but if your Exchange 5.5 servers are SAN-attached now, implementing clustered Exchange servers for Exchange 2000 will be a breeze (I use the term "breeze" loosely).

Highly reliable and scalable storage technologies for Exchange will be the key to future successes for enterprise deployments. When you start to consider Exchange 2000, backup and restore, clustering, and the long-put-off need to consolidate your Exchange servers, SAN-based technology will be the foundation to build upon. Spend time with your favorite hardware vendors and find out where they're at with SANs and Exchange. Plan on storage technology such as SANs as the cornerstone of your plans.