Best Practices SQL Server Transaction Log
Background
In SQL Server Database Recovery model will decide how the transaction log will be logged in transaction log file. Transaction log file extension is .LDF
Full – Transaction log is fully logged (Can take log backup)
Bulk Logged – Bulk transaction is minimally logged (Can take log backup)
Simple – Transaction log will be truncated on checkpoint
In transaction log file transactions are sequentially logged, every record in transaction log file is uniquely identified by log sequence number (LSN). LSN data type is Numeric (25,0)
You can follow below best practices for the transaction log file
1. Don’t create multiple log files : As transactions will be logged into log file sequential manner it would not help for data stripping across multiple files
2. Keep the transaction log file on the separate drive
3. Identify the RPO and RTO for the database and according to that choose the recovery model and correct log backup strategy
4. RAID 1 + 0 is high recommended for transaction log
5. AUTO SHRINK should be always off on the database
6. Pre-allocate the space to transaction log file, it will improve the performance. Don’t depend on the auto growth option.
7. Always set the values of Initial size, max size and growth property of the transaction log file
8. Always set auto growth value, don’t set in percentage
9. Transaction Log file internal fragmentation can also lead the performance and database recovery issue. Database should not have an excessive number of Virtual Log Files (VLFs) inside the Transaction Log. Having a large number of small VLFs can slow down the recovery process that a database goes through on startup or after restoring a backup. Make sure transaction log initial size and log growth defined well to avoid internal fragmentation
10. External fragmentation can be removed by using disk defragmentation utility
11. In case of Transaction log full, please use below query to check the cause of the log full and take the decision accordingly.
SELECT name ,
recovery_model_desc ,
log_reuse_wait_desc
FROM sys.databases
WHERE name = @DatabaseName
Background
In SQL Server Database Recovery model will decide how the transaction log will be logged in transaction log file. Transaction log file extension is .LDF
Full – Transaction log is fully logged (Can take log backup)
Bulk Logged – Bulk transaction is minimally logged (Can take log backup)
Simple – Transaction log will be truncated on checkpoint
In transaction log file transactions are sequentially logged, every record in transaction log file is uniquely identified by log sequence number (LSN). LSN data type is Numeric (25,0)
You can follow below best practices for the transaction log file
1. Don’t create multiple log files : As transactions will be logged into log file sequential manner it would not help for data stripping across multiple files
2. Keep the transaction log file on the separate drive
3. Identify the RPO and RTO for the database and according to that choose the recovery model and correct log backup strategy
4. RAID 1 + 0 is high recommended for transaction log
5. AUTO SHRINK should be always off on the database
6. Pre-allocate the space to transaction log file, it will improve the performance. Don’t depend on the auto growth option.
7. Always set the values of Initial size, max size and growth property of the transaction log file
8. Always set auto growth value, don’t set in percentage
9. Transaction Log file internal fragmentation can also lead the performance and database recovery issue. Database should not have an excessive number of Virtual Log Files (VLFs) inside the Transaction Log. Having a large number of small VLFs can slow down the recovery process that a database goes through on startup or after restoring a backup. Make sure transaction log initial size and log growth defined well to avoid internal fragmentation
10. External fragmentation can be removed by using disk defragmentation utility
11. In case of Transaction log full, please use below query to check the cause of the log full and take the decision accordingly.
SELECT name ,
recovery_model_desc ,
log_reuse_wait_desc
FROM sys.databases
WHERE name = @DatabaseName
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