Introduction

In SQL Server, Virtual Log Files (VLFs) are smaller segments within a physical transaction log file. They are used to manage and organize the transaction log efficiently. Here’s a concise overview:

Key Points about VLFs:

  1. Structure:
    • Each physical transaction log file is divided into multiple VLFs.
    • The number and size of VLFs are determined dynamically when the log file is created or extended.
  2. Purpose:
    • VLFs help SQL Server manage log space efficiently by allowing portions of the log to be reused or truncated as needed.
  3. Performance Impact:
    • Having too many VLFs (due to frequent small log file growths) can degrade performance, especially during recovery or log backups.
    • Conversely, very large VLFs can delay log truncation and impact performance.
  4. Best Practices:
    • Pre-size transaction log files to avoid frequent auto-growth.
    • Use a reasonable growth increment (e.g., 512 MB or 1 GB) to prevent excessive VLF creation.
  5. Monitoring:
    • You can monitor VLFs using the DBCC LOGINFO command or tools like SQL Server Management Studio (SSMS).

By effectively managing VLFs, you can optimize SQL Server’s performance and ensure smooth transaction log operations.

2. Configuration

All databases receive a VLF reduction (VLF > 1000)

Regular Schedule: After full backup job of Every Saturday at 10:30PM