Criteria for a Reliable Back-End Storage Solution


Topic Last Modified: 2006-05-23

As you plan your Exchange 2003 storage strategy, you must balance three criteria: capacity, availability, and performance. The choices you make as you plan and implement your storage solution affect the cost associated with administration and maintenance of your Exchange 2003 organization.

  • Capacity   In Exchange 2003, your total capacity is approximately equal to the number of mailboxes multiplied by the amount of storage allocated to each mailbox. If your organization is supporting public folders, you must add the appropriate amount of disk space to accommodate public folder storage.

  • Availability   The level of e-mail availability your messaging system requires depends on your business needs. For some companies, e-mail usage is light and considered non-essential. However, for many companies today, e-mail is a mission-critical service. The priority that your company places on e-mail determines the level of investment and resources allocated to a consistently available e-mail solution. Overall availability is increased by redundancy. Redundancy can mean that you should cluster applications to provide CPU redundancy or implement a redundant array of independent disks (RAID) solution to provide data redundancy.

  • Performance   Performance requirements are also unique to each organization. This section refers to performance as it relates to throughput and latency. With regard to storage technology, throughput is measured by how many reads and writes per second a storage device can perform. Latency is measured as the time in milliseconds that a transaction takes to complete a read or write operation.

Before you design your storage solution for Exchange 2003, determine how your company prioritizes these three criteria, especially when considering a balance between availability and performance.

By default, when you install Exchange 2003, all data is stored locally on the drive on which you install Exchange. To determine the capacity, level of availability, and performance associated with this default configuration, you must consider the following factors:

  • Number and speed of CPUs

  • Amount of RAM

  • Server type (such as mailbox server, public folder server, and connector server)

  • Number of physical disks

Because of the many variables in determining server sizing and capacity, use the tools described in "Exchange Capacity Planning Tools" in System-Level Fault Tolerant Measures. In general, if the default configuration does not meet your requirements, you should plan a new storage solution that maximizes capacity, performance, and availability.