Saturday , September 22 2018

Can we enable Circular logging on Exchange database which has Database Copies

It’s a good question . There are few situations like . where storage is filling up faster because of log files . where databases having more database copies . and there is no enough storage available to withstand the situation.

So we will be forced to enable Circular logging in these situation, still its not recommended to do so .

image

What is Circular logging ?  – for starters

To prevent a buildup of log files, you enable circular logging for your replicated databases. When you combine circular logging with continuous replication, you have a new type of circular logging called continuous replication circular logging (CRCL), which is different from Extensible Storage Engine (ESE) circular logging. Whereas ESE circular logging is performed and managed by the Microsoft Exchange Information Store service, CRCL is performed and managed by the Microsoft Exchange Replication service. When enabled, ESE circular logging doesn’t generate additional log files and instead overwrites the current log file when needed. However, in a continuous replication environment, log files are needed for log shipping and replay. As a result, when you enable CRCL, the current log file isn’t overwritten and closed log files are generated for the log shipping and replay process.

 

So the question is , is it safe ? to Enable circular logging in Exchange Databases which are mounted ?

Yes,  And not all the databases in one shot – – It may get your replication network down (Totally depends on the your situation, Read through )

 

If I enable circular logging in Exchange 2013. is my logs are going purge itself ?

Yes , It will be purged automatically by information store service.

 

Is all my database copies logs will be purged ?

Yes , it re synchronizes the logs and it will be purged in all database copies , it may few hours depends on the database size.

Example : Like 200 GB of database with 300 GB logs takes 3 to 4 hours in Blade servers

 

is it safe to enable Circular logging in business hours ?

No, Its totally depends on the size of the logs file you have with your databases , If there are more GB’s of log files .(they are going to resynchronize) which will increase more bandwidth on the replication network.

Still if the databases is too busy in Read/write data. it will put more load on storage in the process of removing those old log files

 

Will I Need to restart information store service ?

No , It should react in few minutes and resynchronize the logs in few hours . (In my case it didn’t require a restart, I cannot assure in all the environments)

 

How to Enable Circular logging in a database ?

To Enable :

Set-MailboxDatabase “DatabaseName” -CircularLoggingEnabled:$True

To Disable:

Set-MailboxDatabase “DatabaseName” -CircularLoggingEnabled:$False

 

To Enable Circular logging in all databases

Get-mailboxdatabase | Set-MailboxDatabase  -CircularLoggingEnabled:$True

To Disable Circular logging in all databases

Get-mailboxdatabase | Set-MailboxDatabase  -CircularLoggingEnabled:$False

 

Hope this article was informative Smile

About Satheshwaran Manoharan

Satheshwaran Manoharan is an Microsoft Exchange Server MVP , Publisher of CareExchange.in
Supporting/Deploying/Designing Microsoft Exchange for some years.
Extensive experience on Microsoft Technologies.

Check Also

Enable Opportunistic TLS with IronPort

Enabling Opportunistic TLS on your Anti spam Devices A method which can described as “best ...

5 comments

  1. S.Nithyananadham

    Hi Sathesh,

    Thanks for writing an wonderful article .

    I just wanted to clarify few of my queries . Please correct me if i am wrong .

    what do you mean by closed log files ? whether it is an new transaction log file will get created after renaming the current log ?

    Thanks
    S.Nithyanandham

  2. Hi Sathesh,
    Great site. I love it!
    My Exchange stopped because of log-build up. Can I enable CRCL on all database copies and DAG at the same time?
    Thank you!
    kris

  3. Hi Sathesh,

    Thanks for sharing the knowledge.
    So we have 2 Mailbox servers in DAG and one has died. LOGs drive filling up very fast, can we enable circular logging?

    Thanks

    Vicky

Leave a Reply

Your email address will not be published.