Offline Defrag

Why you need to defrag the database in the first place ?
Exchange Server performs a daily automated defragmentation as a part of its scheduled maintenance. While this online defragmentation helps to keep the database performing well, it does nothing to shrink the database's physical size. Instead, it leaves empty space within the database, which Exchange can later reuse. The only way to get rid of this white space and shrink the database size is to take the database offline and run the ESEUTIL /D command. (offline Defragmentation)

You can use the Eseutil utility to defragment the information store and directory in Microsoft Exchange Server 5.5 and to defragment the information store in Microsoft Exchange 2000 Server and in Microsoft Exchange Server 2003. Eseutil is located in the Winnt\System32 folder in Exchange Server 5.5 and in the Exchsrvr/Bin folder in Exchange 2000 and in Exchange 2003. The utility can run on one database at a time from the command line.

Commands:
Defragmenting an Exchange 2000 or Exchange 2003 database
To defragment an Exchange 2000 or Exchange 2003 database, follow these
1. In Exchange System Manager, right-click the information store that you want to defragment, and then click Dismount Store.
2. At a command prompt, type the following commands, and then press ENTER after each command: cd Exchsrvr\Bineseutil /d
Include 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
From my experience this process will run at the speed of 5GB per Hour.
And you will need to do a isinteg after defragmentation process completes.
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Note
To defragment a database, you must have free disk space that is at least 110 percent the size of the database that you want to process. To determine the free space that is required, follow these steps:
1.
Verify that the information store service is not running.
2.
At a command prompt, type the following command, and then press ENTER:
eseutil /ms"database.edb”
3.
Calculate the free space by multiplying the number of free pages by 4 KB.
4.
Subtract the figure that you obtained in step 3 from the physical size of the database.
5.
The figure that you obtained in step 4 represents the data in the database. Multiply this figure by 1.10 (110 %). The sum total is the space that you require to defragment the database.
Backups:
Because offline defragmentation rearranges the data in the Exchange databases, use the Backup utility immediately after defragmentation to create standard backups of the databases that secure the new data arrangement. Earlier incremental or differential backups are no longer useful because they refer to database pages that were rearranged by the defragmentation process.

Disk Space Constrain to run offline defrag ?
If you really do not have enough free space try the Eseutil /d /t "f:\temp.edb". Where the f drive has enough free space. You can also use a mapped drive but its bit risky. The LAN connection should be good and stable