Avamar: SQL backups failing due to poor Database Consistency Check performance

Summary: This article provides steps to resolve SQL backup failures in Avamar when the Database Consistency Check option is enabled. The consistency check process can impact backup duration, leading to timeouts, especially for incremental backups. ...

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Symptoms

  • Consistency check is enabled for all SQL backup types (Full, Incremental, Differential): 
    • <flag type="checkbox" pidnum="3006" value="true" name="consistency-check" />
  • Incremental backups with a 1-hour backup window consistently time out and fail to complete.
  • Full backups take over 2 hours to complete.
  • Without consistency-check enabled:
    • Full backups complete in ~12 minutes.
    • Incremental and transaction log backups complete in 2–3 minutes.
    
        
    Cause
    
        
    The Avamar avsql plug-in performs Database Consistency Checks sequentially on individual databases, resulting in suboptimal performance.
    
  
    Execution flow:
    
  
      
   
    1. The system enqueues the database task with status ENQUEUED.
      2. 
   
    2. A thread dequeues the task and starts the consistency check.
      3. 
   
    3. After the check, backup streams are spawned for that database.
      4. 
   
    4. The system waits for all streams to start before enqueuing the next database task.
      5. 
   
    5. Steps 2–4 repeat for each database
      6. 
  
    
  
    This serialized approach delays backup stream initiation and contributes to timeouts.
    
        
    Resolution
    
        
    If the consistency check takes a long time, then disable the SQL consistency check within Avamar Dataset. This should be done especially for Incremental backups. 
    
  
    <flag type="checkbox" pidnum="3006" value="false" name="consistency-check" />
    
  
     Run it manually from SQL Management Studio as following query:
    
  
    DBCC CHECKDB ('database_name')
    
  
    Useful options are:

    
  
    DBCC CHECKDB database_name
DBCC CHECKALLOC database_name
DBCC TEXTALL database_name
DBCC CHECKCATALOG database_name
    
  
    More details at:
https://docs.microsoft.com/en-us/sql/t-sql/database-console-commands/dbcc-checkdb-transact-sql?view=sql-server-ver15  (External Link) 
    

            


        

        
        
    Affected Products
    
        Avamar, Avamar Plug-in for SQL



    



                        
    
                            
    
    
    
        
    
            
    
                
                    
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    Article Number: 000167096
    
                
    
                
                
    
                        
    Article Type: Solution
    
                
    
                
    
                        
    Last Modified: 22 Oct 2025
    

                
    
                    
    
                            
    Version:  5
    
                    
    

            
    

        
    
    
    
    
    
        
    
            
    
                
                    
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