Virtual Log File – Video

Virtual Log Files (VLFs) in SQL Server are smaller, manageable segments of the physical transaction log file used to track database changes for recovery and consistency. When a transaction log grows, SQL Server divides it into VLFs to simplify log management, with each VLF handling a portion of the log records. The number and size of VLFs depend on the log file’s initial size and growth increments, and having too many or too few can impact performance—excessive VLFs cause fragmentation, while overly large ones slow log operations. SQL Server reuses VLFs after transactions are committed and log backups are taken in certain recovery models, but poor configuration, like frequent small growth increments, can lead to inefficiencies. Proper log file sizing and maintenance are crucial to optimize VLF performance and ensure smooth database operations.

Related Links

• VLF Best Practices
• What are VLF’s and why should you care?
• VLF Report in Database Health Monitor
• VLF Podcast
• Visualizing VLF’s the old way
• Best Practices Video (VLFs)