Exchange – No log files can be truncated.


In Exchange 2007 we introduced the ability to perform passive replica backups of an Exchange database.  In conjunction with this change we introduced a new method of determining when log files can be truncated.  Starting with Exchange 2007 log files are either truncated through the Information Store service or through the replication service.

 

The information store service method of log truncation handles databases that do not have passive copies.  This is true for all versions of Exchange never than Exchange 2007. 

 

The replication service method of log truncation handles databases that have passive copies.  This may be Cluster Continuous Replication in Exchange 2007 or Database Availability Groups in Exchange 2010 and Exchange 2013.  Some customers have reported that during backup operations log files do not truncate.  The reason for the lack of truncation may vary, but the following event is noted and often attributed to the log truncation failure.

 

Log Name:      Application
Source:        ESE
Date:          8/22/2015 12:08:14 AM
Event ID:      225
Task Category: ShadowCopy
Level:         Information
Keywords:      Classic
User:          N/A
Computer:      MBX-1.domain.com
Description:
Information Store - DAG-DB0 (1444) DAG-DB0: No log files can be truncated. 

For more information, click http://www.microsoft.com/contentredirect.asp.
Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
  <System>
    <Provider Name="ESE" />
    <EventID Qualifiers="0">225</EventID>
    <Level>4</Level>
    <Task>16</Task>
    <Keywords>0x80000000000000</Keywords>
    <TimeCreated SystemTime="2015-08-22T04:08:14.000000000Z" />
    <EventRecordID>6500729</EventRecordID>
    <Channel>Application</Channel>
    <Computer>MBX-1.domain.com</Computer>
    <Security />
  </System>
  <EventData>
    <Data>Information Store - DAG-DB0</Data>
    <Data>1444</Data>
    <Data>DAG-DB0: </Data>
  </EventData>
</Event>

 

When a database has a passive copy and a backup is performed, a do not truncate flag is passed into the information store service.  This is by design since the information store processes no longer handle truncation.  This invokes the event ID 225 to be logged via the ESE / information store process indicating that no log files will be truncated.  When reviewing further events after the 225 the following event is logged:

 

Log Name:      Application
Source:        MSExchangeRepl
Date:          8/23/2015 12:05:15 AM
Event ID:      2046
Task Category: Exchange VSS Writer
Level:         Information
Keywords:      Classic
User:          N/A
Computer:      MBX-1.domain.com
Description:
The Microsoft Exchange Replication service VSS Writer instance 293bac52-7e3a-4600-8c21-784e6dc2d0c9 has successfully completed the backup of database 'DAG-DB0'. 

Database log truncation has been requested for this database. Log truncation will occur on the active copy after the next log generation is created. Log truncation will occur automatically on the passive copies after that log file is copied.
Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
  <System>
    <Provider Name="MSExchangeRepl" />
    <EventID Qualifiers="16388">2046</EventID>
    <Level>4</Level>
    <Task>2</Task>
    <Keywords>0x80000000000000</Keywords>
    <TimeCreated SystemTime="2015-08-23T04:05:15.000000000Z" />
    <EventRecordID>6514781</EventRecordID>
    <Channel>Application</Channel>
    <Computer>MBX-1.domain.com</Computer>
    <Security />
  </System>
  <EventData>
    <Data>293bac52-7e3a-4600-8c21-784e6dc2d0c9</Data>
    <Data>DAG-DB0</Data>
  </EventData>
</Event>

 

This event comes from the replication service VSS writer and confirms that log truncation will occur if all pre-requisites are meant.

 

The ESE 225 event can be safely ignored and is not an indication of the potential success or failure of log truncation for replicated databases.


Comments (4)

  1. turbomcp says:

    Thanks
    always good t remember these things

  2. TIMMCMIC says:

    @TurboMCP

    NP

    TIMMCMIC

  3. Events that can be ignored are the favorite ones.

  4. TIMMCMIC says:

    @Thomas…

    Hopefully they will be ignored now. Unfortunately in recent weeks there has been a lot of troubleshooting to the 225 event…but there’s nothing to fix…

    TIMMCMIC

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