Topic Last Modified: 2007-01-17

The Microsoft® Exchange Server Analyzer Tool queries the CIM_DataFile Microsoft Windows® Management Instrumentation (WMI) class to determine the value of the FileSize key for each Exchange information store database. If the combined size of an information store's .edb file and .stm file exceeds 100 gigabytes (GB), a warning is displayed.

Microsoft recommends that information store databases grow no larger than 50 GB. Assuming proper maintenance, there are no operational issues with running mailbox stores larger than 50 GB; however, backup and restore times may make larger mailbox stores unsuitable for some service level agreements (SLAs).

If you run mailbox stores larger than 50 GB, verify that your hardware is matched appropriately with the service level agreement such that restoration of large databases is within your SLA. Otherwise, it is recommended that you distribute mailboxes across multiple mailbox stores so that no single mailbox store is over 50 GB in size.

To correct this warning

  1. Consider moving some of the mailboxes from the large information store to a new information store on this or another Exchange Server computer.

  2. If you have recently moved mailboxes from this information store to another store, or if you have recently deleted mailboxes from this information store, performing an offline defragmentation may decrease the size of the files.

  3. Consider setting mailbox or message size limits to prevent unlimited growth of the information store database.

For more information about .stm and .edb files, see the Microsoft Knowledge Base article 232323, "Native Content Storage in Microsoft Exchange" (

For more information about moving mailboxes in Exchange Server 2003, see the Knowledge Base article 821829, "Moving Mailboxes in Exchange Server 2003" (

For more information about moving mailboxes in Exchange 2000 Server, see the Knowledge Base article 328810, "Moving mailboxes between servers" (

For more information about performing an offline defragmentation of an Exchange Server database, see the Knowledge Base article 328804, "How to Defragment Exchange Databases" (

For more information about setting message size limits, see the Knowledge Base article 322679, "Set Size Limits for Messages" (