The SQL Server transaction log is a record of all database activity. The size of this file grows as the number of transactions increases. However, upon completion of a transaction log backup, this file clears those transactions that have already been committed in the database. Although the number of transactions in the log is decreased through this process, the size of the transaction log does not change. The file size remains large, with most of it being “empty.” This file size should remain stable as long as transactional throughput is consistent and log backups are taken on a regular basis. The amount of free space should be recorded to ensure consistency of space for the drive and transaction log.
Windows Explorer can be used to view the amount of free space on the drive containing the transaction log. This should be recorded as well.