During mail synchronization, the Exchange transaction logs are taking a large amount of disk spac (30640)

During migration and synchronization the Exchange  transaction log is growing rapidly and sometimes consuming all available space. In worst case scenarios the Exchange server is running out of space and shutting down. Why is this happening and what can be done to prevent this behavior?

This behavior is expected during migration and this has been addressed in Quest documentation.

For EMW this can be found on page 21 of the Best Practices documentation

For QMM this can be found on page 24 of the Best Practices documentation

Quote from EMW Best Practices:

Migration of all the mailbox and public folder data to the target servers at approximately the same time makes the transaction logs for Exchange 2003 private and public information stores grow. Run normal backup procedures to delete the transaction logs throughout the migration on both the source and the target Exchange servers. If normal backup operations do not delete the transaction logs, then you should ensure that appropriate disk space is reserved for the expected transaction log growth. Alternatively, you can enable circular logging during the migration to avoid transaction log growth.

Quote from QMM Best Practices:

When Quest Migration Manager for Exchange synchronizes mail and public folders, for every megabyte of data migrated from the source to the target, a transaction log file of equal size is generated on the target Exchange 2000/2003 server. Exchange-aware backup applications purge the transaction logs after the backup completes. By the time the backup finishes, all logged transactions have already been applied to the store and backed up to tape, making log cleaning safe. Run normal backup procedures to delete the transaction logs throughout the migration on both the source and the target Exchange servers.   If normal backup operations do not delete the transaction logs, then you should ensure that appropriate disk space is reserved for the expected transaction log growth. Alternatively, you can enable circular logging during the migration to avoid transaction log growth. However, Microsoft recommends that circular logging be turned off on Exchange servers. If circular logging is turned on, bear in mind that large transaction logs can still be generated on the Exchange server, and watch closely that the logs are properly cleaned after backup. Keep in mind that if you use circular logging, only full backups can be performed. For more information, refer to Microsoft Knowledge Base article 147524 - XADM: How Circular Logging Affects the Use of Transaction Logs - http://support.microsoft.com/kb/147524.