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Previously, using lower end storage subsystems in production Exchange Server environments was unheard of, but Exchange 2010's reduced I/O requirements make storage options such as SATA drives practical. And Exchange Server 2010 is flexible in terms of the types of storage it can use; it will work with direct-attached storage (DAS) or storage-area network (SAN) storage (or with an iSCSI connection to a storage pool). However, Microsoft does prevent you from storing Exchange Server data on any storage device that must be accessed through a mapped drive letter. So you won't be able to store a mailbox database on a network-attached storage (NAS) system unless it supports iSCSI connectivity.
Even though low-cost storage might provide adequate performance, it's still important to choose a storage subsystem that also meets your organization's reliability requirements. For instance, if you opt for SATA storage, it's best to create a fault-tolerant SATA array. Microsoft recommends using RAID 1+0 arrays. Some organizations use RAID 5 because it's less costly and still provides fault tolerance, but RAID 1+0 arrays generally offer better performance.
It's worth noting that database size can have a direct impact on performance. As a general rule, mailbox databases on standalone mailbox servers should be limited to 200 GB or less. If a mailbox database grows larger than 200 GB, you may benefit from dividing the database into multiple,
Determining storage requirements
Determining the storage requirements for an Exchange 2010 deployment can be a big job, but Microsoft offers a free tool that can help. The Exchange 2010 Mailbox Server Role Requirements Calculator is an Excel spreadsheet that calculates your Exchange storage requirements based on your organization's Exchange usage.
To use the Exchange 2010 Mailbox Server Role Requirements Calculator, fill in a series of cells by answering questions related to the intended Exchange Server configuration and usage. For instance, the spreadsheet asks questions about the average size of an email message and the number of messages users send and receive each day. Formulas built into the spreadsheet will use the information you provide to determine the required storage architecture.
Keep in mind, however, that while the Exchange 2010 Mailbox Server Role Requirements Calculator may be the best tool available for estimating Exchange mailbox server storage requirements, the recommendations it offers are only as accurate as the data you provide. To compensate, Microsoft recommends you provision enough disk space to accommodate at least 120% of the calculated maximum database size.
This was first published in April 2011