The SQL Server sp_spaceused stored procedure is useful for finding out a database size, unallocated space, etc. However (as far as I can tell), it does not report that information for the transaction log (and looking at database properties within SQL Server Management Studio also does not provide that information for transaction logs).
While I can easily find the physical space used by a transaction log by looking at the .ldf file, how can I find out how much of the log file is used and how much is unused?
Found the answer just after I submitted the question :)
It looks like dbcc sqlperf(logspace) and dbcc loginfo are my friend.
http://www.mssqltips.com/tip.asp?tip=1225
Another way - perform in MS SQL Management Studio the following command:
and select File Type = Log you will not only see the file size and % of available free space.
For a more GUI approach SQL Management studio can create a disk space (amongst others) report for a database (right click on the database node in the object explorer, select reports).
This report will also show information on recent file resizes.
Another way - fire up perfmon and check out the following counters:
These values update in real-time.