MORE INFORMATION
The fragmentation of Exchange data occurs on a different level than regular
disk fragmentation. The fragmentation of Exchange data occurs within the Exchange database itself. If you run regular disk defragmentation on an Exchange computer, you should do it during off-hours and preferably with Exchange databases stopped. Disk defragmentation is a very I/O intensive process. Therefore, the Exchange database engine could have difficulty accessing the hard drives in a timely manner.
By default, Exchange databases run a defragmentation process daily. The defragmentation option makes used storage contiguous, eliminates unused storage, and compacts the database. This reduces the database's size. Eseutil copies database records to a new database. When defragmentation is complete, the original database is deleted or saved to a user-specified location, and the new version is renamed as the original. If the utility encounters a bad record, the utility stops and displays an error message.
Online defragmentation
Exchange database online defragmentation occurs automatically as part of the database maintenance process. Online defragmentation detects and removes database objects that are no longer being used. The online defragmentation process provides more database space without changing the file size of the database. By default, Exchange is configured to run online defragmentation daily between 01:00 and 05:00.
Note To increase the efficiency of maintenance and backup processes, you may want to schedule your maintenance processes and backup operations to run at different times.
To schedule database defragmentation, use one of the following methods:
- To schedule database defragmentation for an individual database, use the Maintenance interval option on the Database tab of a mailbox store or of a public folder store object to configure the maintenance interval.
- To schedule database defragmentation for a collection of mailbox stores and of public folder stores, use the Maintenance interval option on the Database (Policy) tab of a mailbox store or of a public folder store policy to configure the maintenance interval.
Offline defragmentation
Although online defragmentation provides some additional database space, you must defragment the Exchange database offline to reduce the physical size of the Exchange database. Eseutil is an Exchange utility that you can use to defragment, to repair, and to examine the integrity of Exchange databases. You can use the Eseutil utility (Eseutil.exe) to perform offline defragmentation when your mailbox stores and public folder stores are offline.
For example, you might perform offline defragmentation if you recently moved many users from a server that is running Exchange. In that case, offline defragmentation reduces the size of the Exchange databases by rearranging the data on the server's Exchange databases and discarding any unused database pages.
Note 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.
By default, the
Eseutil /d command defragments a database by creating a new database, copying the old database records to the new one, and discarding any unused database pages. This creates a newly organized compact database file.
Use the following database switch to run Eseutil defragmentation on a specific database:
eseutil /d Database_Name [options]
Iwhere
Database_Name is the file name of the database that you want to compact.
You can run Eseutil with the
/d /p option at the command line to configure Eseutil to create the new defragmented database in a separate location, such as a location on a different hard disk. If you turn off instating, the offline defragmentation process preserves the original database uncompacted, and the temporary file that is created is the defragmented version of the database. For example, you could turn off instating by using the
/d /p option. Unlike the standard offline defragmentation process (
Eseutil /d), if you run Eseutil with the
/d /p option, the original database is not overwritten with the new defragmented database when the offline defragmentation process is completed.
The
/d /p option can also significantly reduce the time that is required to defragment large databases because you do not copy the defragmented database from the temporary location and overwrite the original fragmented file. However, if you want to mount the defragmented database after you use this option, you must manually move the defragmented .edb and .stm files into the database path and rename them to the correct database file names.
For example, if Tempdfg.edb and Tempdfg.stm are the defragmented files that you created by running the
/d /p option, you must rename them to Priv1.edb and Priv1.stm respectively if Priv1.edb and Priv1.stm are the databases that you originally ran Eseutil against.
The following example command defragments a database that is named Mailbox Store.edb and its accompanying streaming file, turns off instating, and creates the defragmented databases on the D drive. Notice that there is no space after
/t.
eseutil /d /p "c:\program files\exchsrvr\mdbdata\mailbox store.edb" /t"d:\tempdfg.edb"
If you do not use the
/t option, the Tempdfgxxxx.edb file and the Tempdfgxxxx.stm file are created in the location that you run Eseutil from. In the previous file names, xxxx is a random number.
Additionally, you may want to use the following options when you use Eseutil to defragment the Exchange databases:
| Option | Description |
| /b Database | Make a backup copy under the specified name
|
| /tDatabase | Set the temporary database name (the default is
Tempdfrg.edb) |
| /sFile | Set the streaming file name (the default is NONE) |
| /fFile | Set the temporary streaming file name (the default
is Tempdfrg.stm)
|
| /p | reserve the temporary database (in other words,
do not instate)
|
| P/o | Suppress logo |
| /i | Do not defragment streaming file |
Note The Tempdfrg.edb file is created on the logical drive where the eseutil
/d command is run unless you use the
/t switch. For example, to create a Tempdfrg.edb on the root of drive D, run the following command:
You can also use the
/t switch to set the name for the temp database and for a different location. For example, to create a Sample.edb on the root of drive D when you are running the eseutil command from drive C, run the following command:
C:\>eseutil /d /ispriv /td:\Sample.edb
If instating is disabled, the original database is preserved uncompacted, and the temporary database contains the defragmented version of the database.
For example, instating is disabled when you use the
/p option.
Back up the database
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. For more information about backup types, visit the following Microsoft Web site to download the Exchange Resource Kit:
Defragmenting an Exchange 2000 or Exchange 2003 database
To defragment an Exchange 2000 or Exchange 2003 database, follow these steps:
- In Exchange System Manager, right-click the information store that you want to defragment, and then click Dismount Store.
- At a command prompt, type the following commands, and then press ENTER after each command:
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
Defragmenting an Exchange Server 5.5 database
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:
- Verify that the information store service is not running.
- At a command prompt, type the following command, and then press ENTER:
eseutil /ms"database.edb"
- Calculate the free space by multiplying the number of free pages by 4 KB.
- Subtract the figure that you obtained in step 3 from the physical size of the database.
- 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.
- To determine the approximate time that is required to defragment the database, divide the figure that you obtained in step 3 by 9 GB (9, 000,000,000).
Note
9 GB is the speed at which the Eseutil utility runs.
Use one of the following database switches to run Eseutil on a specific database:
|
| /ds | Directory |
| /ispriv | Private information store |
| /ispub | Public information store |
Use one or more of the following options to specify the operations that you want to perform on the database:
|
| /b Path | Makes a backup copy of the original uncompacted database at the specified location |
| /p | Retains and preserves the original uncompacted database in its original location and stores the new compacted database in the default file Exchsrvr\Bin\Tempdfrg.edb. |
| /tFile_Name | Creates and renames the new compacted database in the specified path. |
| /o | Does not display the Microsoft Exchange Server banner |
To defragment the Exchange Server 5.5 database, follow these steps:
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.
- Use the Services item in Control Panel to stop the service of the database that you want to defragment. The service will be one of the following services:
- For the Exchange Directory database, stop the Microsoft Exchange Directory service.
- For the Exchange Mailbox or Public Folder databases, stop the Microsoft Exchange Information Store service.
- At a command prompt, type the following commands, and press ENTER after each command: Include a database switch, and any options that you want to use with the eseutil command. For example, the following command runs the standard defragmentation utility on the directory and saves the copy in the user-defined file:
C:\winnt\system32>eseutil /d /ds /tc:\dbback\tempdfrg.edb /p