[log_reuse_wait value] 4 [log_reuse_wait_desc value] ACTIVE_TRANSACTION [Description] 
A transaction is active (all recovery models). A long-running transaction might exist at the start of the log backup. In this case, freeing the space might require another log backup. For more information, see "Long-Running Active Transactions," later in this topic. A transaction is deferred (SQL Server 2005 Enterprise Edition and later versions only). A deferred transaction is effectively an active transaction whose rollback is blocked because of some unavailable resource. For information about the causes of deferred transactions and how to move them out of the deferred state, see Deferred Transactions.