Recipe6.10.Determining How Much Whitespace Is in a Database

Recipe 6.10. Determining How Much Whitespace Is in a Database

Problem

You wish to determine how much available "whitespace" exists within a given database.

Solution

Using a graphical user interface

Open the Event Viewer (eventvwr.msc).
Click on the Application event log.
Select View Filter.
In the Event ID box, type 1221 and click OK.
View the most recent occurrence of event 1221 for each mailbox or public folder store.

Using a command-line interface

Dismount the database (see Recipe 6.8).
Run the eseutil command with the /ms switch:
```
> \Exchsrvr\bin\eseutil.exe /ms pathToDatabaseFile 
```
where pathToDatabaseFile is the location (including filename) of the file whose whitespace information you want.
The output of the file dump mode will indicate the amount of database free space in kilobytes.
Remount the database (see Recipe 6.7).

Discussion

Many administrators are keen to understand how much whitespace is contained in their Exchange databases. This space includes database pages that were once allocated but have been freed. In most cases, an EDB/STM file pair will grow steadily over time, but if you've done something to shrink the actual amount of mail data in the file pair (such as moving mailboxes to another server or purging old mail), there may be a substantial amount of disk space allocated to the file but unused by Exchange.

The amount of whitespace is especially important to know in Exchange Server Standard Edition when the database size is approaching the 16 GB limit. Unfortunately, there is no built-in utility to determine the amount of whitespace, so the simplest way to find this information is simply to look in the Application Event Viewer logs for event 1221, an informational event that is logged each night after scheduled online maintenance. Here's a sample from one of our servers:

Event Type:    Information Event Source:    MSExchangeIS Public Store Event Category:    General  Event ID:    1221 Date:        1/4/2005 Time:        3:15:00 AM User:        N/A Computer:BATMAN Description: The database "First Storage Group\Public Folder Store (BATMAN)"  has 1 megabytes of free space after online defragmentation has terminated.

If you run the command-line recipe, you will notice that it's not always the same number as that reported with event 1221; eseutil.exe provides a more accurate estimate (at the cost of having to dismount your database).