During an incremental (delta) backup of Exchange the client may transfer more data than expected. One of the possible causes for this behaviour is Exchange defragmentation that runs as part of scheduled maintenance tasks.
Defragmentation tasks result in the re-ordering of data in these databases and is a reason for the potential increase in the size of sent data from the client.
In order to schedule database defragmentation, please 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/or 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