Tag Archives: Circular Logging

Backup Exec: Exchange Incremental Backup Issue: Circular Logging Enabled – KB10391860


Description:  Exchange Incremental backup jobs are failing due to circular logging being enabled. Circular Logging will be enabled if the drive is low on disk space (about 10% or less)

Common customer description: What causes this issue?

How do you fix this issue?

Probing questions: Do you know the reason for circular logging being enabled?

Steps to isolate: Check disk space – if the disk space is low (about 10% or less), that could explain why it’s enabled

Steps to resolve:

1. Connect to the server

2. We need check to see where the exchange database is located on. Also check the disk to see how low it is.

  • Go to the Exchange Management Console (located on the Exchange server or the SBS server)
  • To locate the database, on the left pane, go to Microsoft Exchange On-Premises>>Organization Configuration>>Mailbox


  • Right-Click on the Mailbox Database and click on Properties


  • On the General Tab, it will shows the database path. Make a note of which drive the database is located on. In this case, it’s the E:

Database path

3. In order to know if you should disable it or leave it be can be tricky. Consult your backup solution and make sure you can enable it.


Barracuda Appliance Incremental Backups Issue: Circular Logging Enabled – KB10391557


Description:  Warnings or Failures about Incremental backups being performed for exchange

Common customer description: My backups are failing, can you fix them?

I received an email that my backups have been failing

I got a call that my backups are failing

Probing questions: Was this recent?

How long have you been receiving these emails and/or phone calls?

Steps to isolate: Check the backup report for the errors and/or warnings

Steps to resolve:

1. Log into Barracuda web console

2.  Check the backup report. What is the error or warning that it generates?

Exchange error

3. Barracuda cannot backup the mailbox when circular logging is enabled

  • Why? When circular logging is enabled, transaction log files that have already been committed to the database are overwritten, preventing the accumulation of logs. The log files are overwritten whether or not a full or incremental backup has been run, and a history of previous logs since the last full or incremental backup is not maintained. This is why, when circular logging is enabled, differential and incremental backups of the Exchange databases cannot be performed (since these types of backups rely on complete history of logs). So basically, with circular logging enabled, only information included in the last full backup can be recovered.

4. To work around this, you will have to create a backup job specifically for the exchange server (if the server is a stand-alone server)

To do that go to the Backup Tab, then to Schedules


5. On the right hand side, go to Add a Schedule


6. Name the backup job (make it obvious – if it’s the exchange call it by the exchange server name)


7. Select the server that you want to back up (in this case, it will be mail2)

select server

8. Select the days you want it to back up


9. Set the time you want it to back up (Barracuda runs in a 24 hour format – military time)

  • Repeat means if you want the backup to run 2 or more times in one day


10. Choose the backup type – in this case we can’t do the incremental or “smart” backups, we will chose Full instead


11. Double-check the configuration. When you think it’s correct, on the top right, look for a green button called Save


Now you have to watch the backups for a bit, since we changed the backups to Full it might start taking up space. Monitor the job to make sure their disk space doesn’t get full.

Since we made a new backup just for exchange, we have to deselect the exchange server from the previous job(s)

1. Go back to step 5 but instead of adding a schedule, edit the existing schedule.

2. There might be a check box that says “backup all computers and data sources” – uncheck that box and unselect the exchange server. (Don’t forget to say save!)

Additional considerations: If there is only one server being backed up (example: server02 is the PDC, BK, MX, DNS, DHCP), switching the backup to Full might not be an option.