Co-location avoids moving information multiple times between servers and clients. Multiple hops can cause Windows security problems, as acknowledged by Microsoft. Clients tend to lose their credentials when accessing the reports site, and may reach the SQL Server as anonymous users and be unable to access the report information.
If co-locating the IIS report server and SQL database server is not possible, you must configure the SQL server to use SQL authentication. You must also configure the file used to create the data link for the reports to use a special SQL account so that the reports can access the MessageStats database as valid consumers.
Exchange tracking logs can grow very large, in the range of 10 to 30 gigabytes and may require compression before the log files are transported to the Task Execution Server for processing. Make the decision to compress tracking logs in consultation with your Exchange administrator. Compressing log files has a very small footprint on the Exchange server.
The MessageStats compression utility (QMSDeployment.exe, QMSCompress.exe) can reduce the size of the tracking log file by up to 80%, which is significant when transporting logs that are gigabytes in size. The compressed logs are not decompressed on the Task Execution Server. They are processed in stream, which means that they do not require extra disk space on the servers for processing.
MessageStats depends on the Exchange tracking logs to deliver the activity and volume-based reports. The Default Gathering task, which includes the tracking log gathering, must not be scheduled until the tracking logs are closed. Typically, tracking logs are closed at midnight UTC, so Exchange objects can be collected at any time during the day. However, those objects will be dated on the UTC date they are retrieved.
A worldwide deployment must be tuned in consideration of business activities. To minimize the impact of data collection, tasks must be scheduled to run during off-business hours for the geographic area from which data is collected.
Tracking logs are copied to Task Execution Servers to be analyzed and summarized into useful information for the activity-related reports. The analysis can create a large amount of information to be stored in the database, which should be located near the server doing the processing.
The following diagram shows how, by positioning the Task Execution Servers geographically near and by connecting to the Exchange servers that contain the information, you can optimize the amount of time required to perform a data collection.