Excessive counts of Virtual Log Files (VLF) in a transaction log can lead to performance problems with the transaction log, including restore and recovery times. Excessive VLFs can occur when a transaction log is resized many times, through autogrowth for example.
The ideal value for this metric should be less than 25; excessively high values (greater than 50) can cause high write times when writing to the transaction log.
If this metric indicates an increased number of VLFs in the transaction log, the transaction log should be rebuilt using the steps outlined in Kimberly Tripp’s blog post, 8 Steps to better Transaction Log throughput. Also see Transaction Log Physical Architecture.
Note: This metric relies on the use of an undocumented DBCC command from Microsoft. The output of this command may change (as it did from SQL Server 2008 to SQL Server 2012), so this script may not work correctly on future versions of SQL Server.
Note: This metric works on SQL Server 2000 SP4 and later versions.Excessive virtual log files in transaction log,