I have two SQL Server 2008 R2 running under database mirroring Synchronized mood. Mirroring is working fine. I noticed the log file is growing big although TLog backup is working and there are no any open active transaction. I have 21 GB left out of 100 GB in the log drive. And also 99.9 % log space is unused and 0.1% is used.
Please advise what necessary steps should I take in order to release the log.