Troubleshooting Transaction Log (das_log) Growth

Products

• Carbon Black App Control

Issue/Introduction

Steps to troubleshoot excessive or unexpected growth of the Transaction Log (das_log).

• Errors in server.log similar to this: 

  The transaction log for database 'das' is full due to 'XXXX'

• Login failure when transaction logs are full. 

  The user name or password you entered is incorrect. Enter a valid user name and password, then try again

Environment

• App Control Server: All Supported Versions
• Microsoft SQL Server: All Supported Versions

Resolution

Important Notes: SQL Server will truncate the Transaction Log only under two scenarios: A checkpoint process when in Simple Recovery Mode (recommended). After a Transaction Log backup occurs in Full Recovery Mode (not recommended). App Control is designed to work with the Simple Recovery Model Full Recovery Model should not be used to avoid a performance penalty and excessive Database Log growth. Full Recovery Model is required for Always On Availability Groups and Database Mirroring. If using Full Recovery Model, more frequent Transaction Log backups must be configured.

 

1. Determine whether Full Recovery Model is truly needed.
   • Unless using Always On Availability Groups or Database Mirroring, the Simple Recovery Model is recommended.
   • Review: Configure App Control for High Availability and Disaster Recovery
2. Verify Transaction Log Backup settings
   • More frequent Transaction Log Backups are required when using Full Recovery Model.
   • Only the Transaction Log Backup will truncate the Transaction Logs.
   • Review: Back up a transaction log
   • Review: Transaction log backups (SQL Server)
3. If using Always On Availability Groups or Database Mirroring
   • When using either of these, the principal server sends the active Transaction Log Records to the mirror server.
   • Once received, the mirror server implements those changes on the mirror database, and the Log Record is then marked Inactive.
   • Any issues (network, performance etcetera) will prevent the Transaction Log from being able to truncate further due to the Active records.
   • Review: Troubleshoot Database Mirroring Configuration (SQL Server)

Additional Information

• Simple Recovery Mode is recommended. See also: Tech Docs > Server OER > App Control Database: SQL Backups.
• Factors that can delay log truncations
• Manage the size of the transaction log file