This metric measures the percentage of used space for transaction log files (LDF files). You’ll find this useful if your SQL Server has limited capacity, so you need to maximize existing disk space utilization by minimizing unused space. It will also alert you if the percentage of used space exceeds the specified thresholds.
It is best practice to pre-allocate the size of the transaction log file whenever you create a new database. This reduces or eliminates the need for autogrowth, which may lead to physical file fragmentation. The size of the file will depend on the number of transactions you expect, and how often you intend to backup the transaction log.
For information on managing your transaction log, see Understanding Logging and Recovery in SQL Server. For details of how to shrink the size of your transaction log, see Recover from a full transaction log in a SQL Server database.
This metric can be used in conjunction with virtual log file monitoring, particularly if you’re using log reader for replication.Percentage of used log space,