Use the following article to determine the amount of space used by the IM Manager database: How to determine the Storage Space Used In the IM Manager Database.

1. Determine if the size is due to the SQL Transaction Logs or Data Logs.

Run the following SQL command against the IM Manager database.  You can use any SQL tool to perform this command.

DBCC SQLPERF(logspace) 
 

This shows the transaction log space in megabytes and the percentage used.

If you feel that the transaction log is too big see the section below on steps to maintaining it.

2. Determine if the size is due to the data for the database.

Run the following SQL command against the IM Manager database.  You can use any SQL tool to perform this command.

sp_spaceused

If you feel that the data portion of the database is too large see the section below on steps to maintaining it.

Managing Size of SQL Transaction Logs

The IM Manager application has no requirements with respect as to the type of transaction log used or the way it is managed. Management of the transaction logs depends on your organizational needs.  The transaction log is critical to maintaining integrity of the database.  You should work with your SQL DBA to determine the best method to manage the transaction log.

Here are article from Microsoft on managing the SQL transaction log:

How to stop the transaction log of a SQL Server database from growing unexpectedly

INF: Shrinking the Transaction Log in SQL Server 2000 with DBCC SHRINKFILE

How to use the DBCC SHRINKFILE statement to shrink the transaction log file in SQL Server 2005
 

How to manage the SQL Server Desktop Engine (MSDE 2000) or SQL Server 2005 Express Edition by using the osql utility
 

Here is a Symantec article on shrinking the SQL and MSDE transaction logs: 

How to Shrink the IM Manager Database Transaction Log on SQL Server and MSDE

Managing Size of Data Portion of the Database

Determine the space used by each IM Manager table by running the following SQL command against the IM Manager database.  You can use any SQL tool to perform this command.

EXEC sp_MSforeachtable @command1="EXEC sp_spaceused '?'"  

Typically the following tables may use large amounts of space:

messages

archived_messages

file_transfers

tempmsgs

impacttracking

See the following KB article to manage the size of the these tables: How to Reduce the Size of the Data in the IM Manager Database (by Purging). 

NOTE: After performing steps to reduce the size of the data in the database the SQL transaction log may be using a large amount of space.  See above for managing the SQL transaction log.

NOTE: If you find other tables using large amounts of space contact Symantec Technical Support. If you wish to understand which tables are using the most space use the GetDiagnostics tool for IM Manager.  The file dbspace.csv contains a list of most tables in the IM Manager database and the space utilization for each.

Technical Information

1. Size of indexes for messages table is large.  This is a known issue.  See the following KB article: IM Manager Database Indexes Use a Large Amount of Space.