Thank You for response. My database operates in synchronous mode. I have two servers working in mirroring mode a thirty server witness. This is MS SQL 2008 R2, The database is in FULL Recovery Model.
Reffering to backup transaction log. The true is I forgot to implement backup transaction logs in my mainanace plans.
The last question is, Can I make shrink transaction log, when database is in mirroring mode ? It's correct ? If Yes then I Use graphical interface (task->shrink file->...) or script:
dbcc shrinkfile('MirroredDb_log', 0);
After when I shrink this file, I planing to implement new mainanace plan: daily backup transaction log - every 15 minutes and weekly.