Log won't truncate when backed up

[ptheriault]

I have a SQL server 2005 instance with a database that has a 13gb log file. I have created and run the following job to backup the log.

BACKUP LOG [1stComp] TO [FirstCompLogDump] WITH NOFORMAT, INIT, NAME = N'1stComp-Transaction Log Backup', SKIP, NOREWIND, NOUNLOAD, STATS = 10
GO

I know this step will also init my backup device. For some reason the log is not truncating. Do I need to add the with truncate command?

I even tried DBCC SHRINKFILE(db_name, 500);

But I won't shrink. I should mention this database is the principal in of a mirror.

 

[ptheriault]

Never mind...It finally trunacted. I guess it had been so long that it had truncated it just took some time.