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Small changes to software might seem insignificant, but they can make life extremely difficult for IT workers, including those responsible for email hosting.

Tony Redmond, writing for Windows IT Pro (News - Alert), has reported on the way Exchange 2013 is now analyzing the size of its databases.

“Apparently there’s quite a lot of overhead within the database that has never been charged against user mailbox quotas,” Redmond wrote. “I assume that the until-now-forgotten overhead includes general debris, forgotten messages, bits of e-mail addresses, and similar crud that accumulates over time. The Exchange developers maintain that they are simply being more accurate in mailbox accounting.”

Exchange 2013’s email hosting store is still based on ESE instead of SQL. Microsoft (News - Alert) touts the reduction in I/O operations for email hosting as an advantage to the new version. It also isolates problems with one mailbox to a single database without affecting other databases stored on the Exchange server.

The change to the way the database is handled increases the size of the email mailboxes by 30 to 40 percent without a subsequent increase in the size the data actually takes up on the disk, which can make it difficult for administrators of previous versions of Exchange to upgrade.

Redmond gives the example of a mailbox that Exchange 2010 highlights as having 100 MB of usage. In Exchange 2013, it might actually contain 130 to 140 MB. Administrators using judicious limits, however, should not have any problems.

Redmond put it bluntly: “For instance, if your quota is 10GB and you’re only using 1GB today, seeing an increase to 1.3GB after your mailbox moves to Exchange 2013 won’t cause any concern. Unless you worry about such things, in which case it’s time to consult with a shrink.”

Ultimately, administrators should in Redmond’s view understand how much data they’ve allocated versus how much data their users are actually using on their email hosting systems. He went on to recommend some PowerShell-based tools in his article.