Defragmenting a database requires free disk space equal to 110 percent of the size of the database being processed.

1. In Exchange System Manager, right-click the information store that you want to defragment, and then click Dismount Store.
2. At the command prompt, change to the Exchsrvr\Bin folder, and then type the eseutil /d command, a database switch, and any options that you want to use.
For example, the following command runs the standard defragmentation utility on a mailbox store database:
C:\program files\exchsrvr\bin> eseutil /d c:\progra~1\exchsrvr\mdbdata\priv1.edb
Use the following database switch to run Eseutil defragmentation on a specific database:
eseutil /d <database_name> [options]

/b<database>   Make a backup copy under the specified name

/t<database>   Set the temporary database name (the default is
               Tempdfrg.edb)

/s<file>       Set the streaming file name (the default is NONE)

/f<file>       Set the temporary streaming file name (the default
               is Tempdfrg.stm)

/p             Preserve the temporary database (in other words,
               do not instate)

/o             Suppress logo

/i             Do not defragment streaming file