Mirroring and Log File Growth

We currently have a 10GB database that is functioning properly mirrored. The only issue we have is that the log files grow very quickly during the early morning hours when a large number of transactions hit our DB from scheduled jobs. We have transaction log backup and shrink job that runs every 3 hours to backup the log and shrink the logical file to 10GB. In most cases this will shrink the log back down to it's desired size of 10GB. However, on some mornings it takes more repetitions of the log backup/shrink job to return the log size back to "normal". During this these times when it does not shrink the DB effectively, I get a report of the job process by email that states "Cannot shrink log file 2 (e_Log) because all logical log files are in use." I run a DBCC OPENTRAN command, and there are no open transactions. Eventually, the log file will return to it's normal size of 10GB through the log file backup job. I have a few questions though.

1. Is this normal behavior during moderate database use?
2. Does mirroring have any effect on the SIZE of the log file?
3. Is it normal for the size of the data file to be smaller than the size of the log file on a heavily used database?
4. Does anyone have any suggestions to better maintain the log file size?

Thank you,
Greg

Mirroring won't affect the log, unless the Principal can't connect to the mirror in which case transactions will queue in the log and may cause issues.

Why are you shrinking your log? It should be as big as it needs to be, i.e. large enough to hold the transactions from your scheduled jobs. Having it auto-grow then re-shinking it is a waste of time and resources (it will slow down your scheduled jobs while the log grows).

The reason you can't shrink it sometimes is because the log actually consists of Virtual Log Files (VLFs). If the active one of these is near the end of the log file, it won't be shrinkable until it moves back to the beginning of the log file due to transactions having happened.

Normally the log file is smaller than the data file, but there may be exceptions. The bottom line is, the log needs to be as big as is required by the size and volume of transactions using the database.

Ensure you have adequate log backups of a suitable frequency all the time, and especially during your batch processing.