Size of the ldf file increasing Possible Duplicate:
  Why Does the Transaction Log Keep Growing or Run Out of Space?  




I have some sql server database for which recovery model is set to full.Now for some databases the ldf size has become large.I tried taking log backup regularly,but i didn’t find decrease in physical size of ldf. I followed what stan20 has told in this link http://social.msdn.microsoft.com/Forums/en-US/databasedesign/thread/704bcfbc-9251-4f4e-9a80-04bc7fe9ae78
But it only reduced logical file size. So how i can mange size of ldf file?
Backing up the transaction log will not shrink the physical file.  It will only mark transactions as inactive and potentially mark virtual log file(s) for reuse.  What you're looking to do is actually shrink the file system file, and this can be done through DBCC SHRINKFILE.

Note: shrinking the transaction log, or any other database file for that matter, should not be a routine database task.  Proper sizing will mitigate the necessity for tasks like this.