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Summary: Circular logging in Exchange Server automatically overwrites transaction log files, conserving disk space. When enabled, log files are limited to 1 MB and overwritten when full. Disabling it is not recommended for data recovery and backups. You can enable it using Exchange Management Console or Shell. Be cautious of storage issues. Third-party tools like an EDB to PST converter can help with data recovery without log files.

In Exchange Server, Circular logging is not enabled by default. Circular logging is a mechanism in which Exchange Server automatically overwrites individual transaction log files once their data has been successfully committed to the database. This proactive approach prevents the transaction log files from continuously growing in size, effectively conserving valuable hard disk space.

The term “circular” refers to the practice of deleting log files on a rotating basis when the disk space limit is reached, following a Last-In, First-Out (LIFO) queue approach.

What Happens When

  • Circular logging is disabled: If circular logging is disabled, each log file goes into the transactional log database and so there is no limit on the maximum size of the database (no limit exists).
  • Circular logging is enabled: While circular logging is enabled, the maximum size of the transactional log files is limited to 1 megabyte (MB). It is implemented by overwriting the previous log files automatically once the maximum limit is reached. Thus, transaction log database does not grow any further.
Important Points to Remember
  • Without a complete set of transactional log files, it is impossible to recover new data. So, circular logging is not recommended in production environments.
  • While doing backups (incremental as well), enabling circular logging on Exchange database is not recommended.
Ways to enable Circular logging in Exchange 2010
  • Using Exchange Management Console
  • Using Exchange Management Shell
Using Exchange Management Console

Enable circular logging in Exchange 2010 using Exchange Management Console with below few steps.

  • Start Exchange Management Console
  • Choose Organization Configuration, expand it and then click Mailbox
  • On Database Management tab, select the database to configure
  • Under database name, in action pane, click Properties
  • Click Maintenance tab > select Enable circular logging check box > click OK
With Exchange Management Shell

For Exchange 2010, you can enable Circular logging by executing the following command:

Set-MailboxDatabase -Identity “Database Name” -CircularLoggingEnabled $true

Note: To make the changes to circular logging settings effective, perform any of two – Restart the Microsoft Exchange Information Storage Service, or Dismount and mount the databases.

Issues you may face with Circular logging

You may encounter a condition where database storage space is filling up continuously. Once you reach a certain threshold point of storage, there could be a failure in mounting Exchange Database. Now, before going to enable circular logging to free up space in your database, you must make a copy of log and database. This must be done to have a backup of the database and to replay the logs again when required.

Can third-party tools help after Exchange data loss?

In the event of data loss, there exist several viable solutions for recovering Exchange Server data. Among these, stands out as a top-tier choice for repairing corrupt Exchange database files, with the added advantage of not needing log files for the recovery process. Additionally, an EDB to PST converter can efficiently extract data from Exchange backup files, offering another effective avenue for data retrieval.

Kernel for Exchange Server