Enable Circular Logging in Exchange 2016/2013 via Powershell & EMC

Why Circular Logging  Needed In Exchange Server?

Circular logging is a technique of preserving hard drive space in MS Exchange transaction logging procedure. Or, it is a process where Exchange server recycles its transaction logs. It allows Exchange to overwrite individual transaction log files. If the circular logging is disabled, each log file goes into the transactional log database and there is no database size restriction. If the circular logging is enabled then, the size of the transactional log can just grow to one megabyte (1MB). After reaching the maximum size limit, the first transaction log is overwritten automatically so that the log database should not be oversized.

Here, ‘Circular’ term is used because the set of log files begins rotating when the limit of disk space is reached. It is somehow similar to LIFO (last-in, first-out) queue. Basically, the circular logging is utilized with Exchange local information protection. It is so because in that mode backup files are not generated hence, a complete transaction log is not important. The circular logging feature is disabled by default in the Exchange 2010. If this option is enabled and the database gets corrupted or compromised then, it is impossible to recover it completely (if some new data has been added recently after the last backup).

Circular Logging – Essential in Exchange Server?

Circular logging is a component of JET ( Joint Engine Technology ) database utilized by all versions of Exchange Server, which can be enabled or disabled via an admin. Whenever an email is conveyed, deleted, sent, or forwarded, Exchange Server writes all information in the log file. The time distinction between database composition and transaction logs is calculated in milliseconds.

Well, Exchange notes down Transaction logs for only one reason; database recovery. If the Exchange database that comprises all your mailbox information has been stopped working then, you will require restoring the database from the most recent backup. Here, the main issue is that the backup copy is not up to date with most recent transactions. This is where transaction logs prove handy. The main purpose of creating log files in Exchange is to store the information of all kind of transactions.

How to Enable Circular Logging in Exchange Server?

There are two different ways to turn on circular logging in Exchange Server:

  • Using Exchange Management Console
  • Enable circular logging via PowerShell

#Approach 1: Enable Circular Logging via Exchange Management Console

Before executing below-mentioned steps, you must entrust the following:

  • Local Administrators group and Exchange Server Administrator role for the target server
  • Now, launch the Exchange Management Console.
  • In the console tree, click on Server Configuration >> Mailbox.
  • In work pane, hit a right-click on the storage group for what you need to enable or disable the circular logging then, click on Properties
  • Storage Group Name wizard will appear now
  • Mark Enable circular logging checkbox and hit the OK button
  • After this, restart Microsoft Exchange Information Store service (ISS). Or, you can dismount and then, mount all databases of the storage group

Important Note: Public folders and mailboxes on a server will unavailable for the user while MS Exchange Information Store service begins restarting. The public folders of a database will be unavailable when the database is dismounting and remounting.

#Approach 2: Using PowerShell to Enable Circular Logging in Exchange

Run the following command to enable circular logging. If you want to disable the circular logging then, execute the below command:

Important Note: When the Microsoft Exchange Information Store service will be restarted the public folders and mailboxes on the server will be unavailable for the users. Also, when a database will start dismounting or remounting, the public folders and mailboxes will be unavailable for the user.

Cons of Circular Logging in Exchange Server

Since every feature has some advantages and disadvantages and circular logging also has:
a) Effect the Capability to Back up & Process of Restore Exchange Mailbox to Server, after enabling the features, Administrator can’t perform the incremental Backup of Exchange Database
b) Chances of Data-loss is high due to the limited amount of transaction logs stored after Circular Logging started.
c) Mostly used when Exchange Server working of Low Space Disk

Summing Up

As it is clear now that the transaction logs exist to perform database restoration and these log files should be stored on a different physical drive than the database. The drives that keep the database sometimes may fail due to various reasons and then, users can utilize the transaction log to retrieve their complete database. Here, we have discussed two different techniques to enable circular logging in any version of Exchange. Users can opt any method according to their suitability and inclination.