Усечение файла лога транзакций.
BACKUP LOG databasename WITH TRUNCATE_ONLY
http://expertanswercenter.techtarget.com/eac/knowledgebaseAnswer/0,295199,sid63_gci980086,00.html BACKUP LOG databasename WITH TRUNCATE_ONLY
DBCC SHRINKFILE should now also be more effective, however if you don't change the recovery model to SIMPLE the log file will just fill up over time again. Search on "Selecting a Recovery Model" in SQL Server Books online for more information.