Exchange 2010 Circular Logging , Circular logging parameter change will not be applied on this database before it is remounted. Dismount and remount database….

You would like to enable CL ( Circular logging) on the production Exchange Servers, perhaps you start moving mailboxes and realized you need to turn on circular login, due to concerns with possible disk space issues, especially with large mailboxes.

Now if you have prior versions of Exchange experience you will quickly remember enabling and disabling it requires IS ( Information store ) service to be restarted in order for CL to go into effect & kick in.

Or perhaps you remember seeing this with Exchange 2010

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Microsoft Exchange Warning
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The following warning(s) occurred while saving changes:

Set-MailboxDatabase
Completed

Warning:
Circular logging parameter change will not be applied on this database before it is remounted. Dismount and remount database "db51elt" in order to apply this parameter change.

From PS we would enable CL with one Liner

###Enabling CL on the Specific DB

Get-MailboxDatabase db01elt | Set-MailboxDatabase -CircularloggingEnabled:$true

###Disabling CL on the Specific DB

Get-MailboxDatabase db01elt | Set-MailboxDatabase -CircularloggingEnabled:$False

Now if we like to enable CL on all the databases we would do this easily

$Alldb = Get-MailBoxDataBase $Alldb | Set-MailboxDatabase -CircularloggingEnabled:$True

*** As you can see we get the same warnings***

If you like to disable it on all Databases ….

$Alldb = Get-MailBoxDataBase $Alldb | Set-MailboxDatabase -CircularloggingEnabled:$False

Now why we are getting warning from ONLY one single DATABASE when we turn on CL on all the databases ? the answer is here in this picture. one DB in here does not have any other DB copy….

Now we need to quickly remember this

Circular Logging TYPE	What is it ?	Managed BY
CRCL	continuous replication circular logging	Microsoft Exchange Replication Service
JET CL	Traditional circular logging	JET circular logging is performed by Information Store

### Jet CL ( Single Database , with or without DAG environment )

Enabling and Disabling Traditional CL requires, Database to be dismounted and mounted. in this case the database does not have any copy within the DAG environment ( see picture above)

### CRCL ( Database in the DAG has its copy on another DAG member)

If the database has a copy , then CRCL comes into play and enabling & disabling it wont require any administrator intervention.

Good news if you are in DAG environment you can take advantage of CRCL , meaning no need to touch database after enabling or disabling CRCL = this will keep end users and your managers happier IMO (-:

Here is more comprehensive information on Scott Article !!!

http://blogs.technet.com/b/scottschnoll/archive/2011/06/27/circular-logging-and-mailbox-database-copies.aspx

Oz Casey, Dedeal

Exchange Server North America MVP

MCITP (EMA), MCITP (SA)
MCSE 2003, M+, S+, MCDST
Security+, Project +, Server +
http://smtp25.blogspot.com/ (Blog)
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