Top Exchange Design Considerations

Of the four subsystems in an Exchange server, the disk subsystem receives the least amount of proper attention. I continually find that administrators spend hours discussing whether the Exchange server should have a 3.2GHz CPU or a 3.4GHz CPU, but spend only a few minutes of consideration on the disk subsystem. Yet everything the Exchange server does involves the disk subsystem in some way. Table 1 provides overall guidance for the design of an Exchange mailbox server disk subsystem for DAS. (For Exchange environments that use NAS or a SAN, you'll need to contact your storage vendor for disk-configuration recommendations.) I don't have the space in this article to cover all the architecture and design options for an Exchange disk subsystem, but I will point out some common mistakes that I run into regularly.

Whether Exchange disk storage uses DAS, NAS, or SAN, the Exchange disk drives shouldn't be shared with or used by other applications. Exchange is sensitive to disk latency, and the inherent random nature of Exchange database activity further amplifies that sensitivity. The Microsoft article " Exchange Server and network-attached storage" (http://support.microsoft.com/?kbid=317173) is a good starting point for learning about the effects of disk sensitivity and disk latency. . . .