Despite the benefits of giving users large electronic mailboxes, many administrators have been reluctant to do so because of the costs and complexity involved. However, those costs can be reduced and that complexity simplified making large mailboxes a more viable solution with Microsoft Exchange Server 2010.

That’s what Microsoft maintains in a recent white paper, “The Microsoft Large Mailbox Vision: Giving users large mailboxes without breaking your budget.” In the document, the company explains how new features in Exchange 2010 can reduce storage costs, as well as improve the operation of existing systems.

What’s wrong with small mailboxes? For one thing, they require user intervention to manage. Users are forced to make decisions on what should be saved, archived or deleted in order to stay within size limits. Not only do those decisions waste valuable time for users, but they can result in important organizational knowledge being trashed.

Faced with the prospect of reviewing an onerous number of emails, some users take shortcuts to avoid the burdensome task. One typical shortcut is dumping emails into .PST files. That creates a whole new set of problems. Universal access to the emails is lost because the files can be accessed only on the machines they were created on. If the files are corrupted, oftentimes there’s no way to recover the data in them. What’s more, since the files are outside the Exchange infrastructure, they can be difficult to search–a serious problem should an organization be hit with an electronic discovery order in a lawsuit.

One way Exchange can reduce the costs associated with larger mailboxes is by allowing organizations to substitute lower performance, higher capacity disk storage for high performance, lower capacity disks.

Disk performance is measured in IO operations per second, or IOPS. A disk can perform a maximum number of IOPS and each Exchange user consumes a  number of them. With Exchange 2007, each user consumes about 0.3 IOPS. Exchange 2010 reduces that number to 0.1 IOPS. That means an organization running Exchange 2010 can have more people access an Exchange server without it taking a hit on performance. So on a 146GB disk rated at 150 IOPS, for example, 500 users with mailboxes with a maximum size of 300MB could be accommodated before disk performance would be affected. With Exchange 2010, though, a cheaper, slower disk with more capacity–say, a 1TB disk rated at 50 IOPS–could be substituted for the higher performing platter and serve 500 users with mailboxes with 2GB limits. Better yet, the 50 IOPS disk can be had for 25 percent of the cost of the 150 IOPS hardware.

“By taking advantage of the increasing capacity in disk technology and combining it with the Exchange Server 2010 IO performance reductions, organizations can reconsider their Exchange storage options and provide large mailboxes for their users without breaking their budgets,” Microsoft asserts.

A problem with using cheaper disk for storage is reliability. They’re likely to fail sooner and more often than high performance disks. That concern was taken into account when designing Exchange 2010. The software has built-in resiliency features based on Database Availability Group technology, or DAG. With DAG, up to 16 mailbox  servers can be used to manage failures. Database copies can be stashed locally to provide high availability and remotely for disaster recovery. Exchange 2010 can automatically switch between database copies to keep an organization humming through any database snafu, such as disk failure. “The built-in Mailbox Resiliency solution enables a system in which nightly backups for recovery purposes are no longer necessary,” Microsoft contends.

When data changes in the active database, it explained, it is reflected in the passive copies of the database. If a database fails, a passive copy will come to the rescue. If a server fails, the functions of its databases will be picked up by copies of them on other servers.

One problem with replication, though, is that accidental changes may be made in the database copies. A file deleted inadvertently on the active database will be deleted on the copies and become unrecoverable. Exchange 2010 deals with that problem in two ways. It has a single item recovery feature for quick correction by administrators of user errors. It also has the ability to create “lagged” copies of the active database so it can be recovered from a particular point in time.

Another resiliency feature of the software is its ability to handle physical disk errors. When the program encounters an error reading or writing to a database, it automatically retrieves the correct data from a copy of the database and repairs the error. What’s more, it re-maps the disk so the damaged block of storage isn’t used again.

“Larger mailboxes are better for users, IT administrators and organizations,” Microsoft argues. “They use today’s storage systems more efficiently. They help users stay productive by giving them better access to the valuable organizational knowledge contained in historical email.”