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Transaction logs filling up disk space RRS feed

  • Question

  • We have a Windows 2008 R2 Enterprise server with Exchange 2010 installed. Normally, after a successful VSS backup the logs get cleared, unfortunately, our Backup System is giving us problems and consequently our disk has filled up with over 23,000 files - over 20GB worth of logs!

    How can we get these transaction logs played back into the Exchange DB and deleted from our hard disk?

    Thanks for your advise.

    Tuesday, August 7, 2012 1:26 PM

Answers

  • Hi

    Under these circumstances the best approach would be to enable circular logging to truncate the logs as soon as they have been written to the database.  It looks like you have a single server (i.e. no DAG) so you will need to dismount then mount the database for this change to take effect.

    Steve

    • Marked as answer by Oliver Buckie Tuesday, August 7, 2012 4:40 PM
    Tuesday, August 7, 2012 1:30 PM
  • Thanks for your quick reply Steve. Should I enable circular logging with the Mailbox database mounted, then dismount and remount? Will this process clear the current 23,000 logs - or will it just stop more logs from being generated?

    If the database is replicated as part of a DAG, then you enable circular logging and it will start the log clearing process automatically after about 5 minutes or so. Logs will continue to generated however. Circular logging will remove them when they are no longer needed.

    If this is a standalone server and the database is not replicated, you will need to dismount and remount the store after enabling circular logging.

    The logs arent "played back" into the store in this process. THey are only replayed when doing a recovery. Something you wont be able to do once circular logging is enabled. Once you get you backups fixed, disable circular logging and get a good backup ASAP.

    • Marked as answer by Oliver Buckie Tuesday, August 7, 2012 4:40 PM
    Tuesday, August 7, 2012 2:47 PM
    Moderator

All replies

  • Hi

    Under these circumstances the best approach would be to enable circular logging to truncate the logs as soon as they have been written to the database.  It looks like you have a single server (i.e. no DAG) so you will need to dismount then mount the database for this change to take effect.

    Steve

    • Marked as answer by Oliver Buckie Tuesday, August 7, 2012 4:40 PM
    Tuesday, August 7, 2012 1:30 PM
  • Thanks for your quick reply Steve. Should I enable circular logging with the Mailbox database mounted, then dismount and remount? Will this process clear the current 23,000 logs - or will it just stop more logs from being generated?
    Tuesday, August 7, 2012 1:46 PM
  • Thanks for your quick reply Steve. Should I enable circular logging with the Mailbox database mounted, then dismount and remount? Will this process clear the current 23,000 logs - or will it just stop more logs from being generated?

    If the database is replicated as part of a DAG, then you enable circular logging and it will start the log clearing process automatically after about 5 minutes or so. Logs will continue to generated however. Circular logging will remove them when they are no longer needed.

    If this is a standalone server and the database is not replicated, you will need to dismount and remount the store after enabling circular logging.

    The logs arent "played back" into the store in this process. THey are only replayed when doing a recovery. Something you wont be able to do once circular logging is enabled. Once you get you backups fixed, disable circular logging and get a good backup ASAP.

    • Marked as answer by Oliver Buckie Tuesday, August 7, 2012 4:40 PM
    Tuesday, August 7, 2012 2:47 PM
    Moderator
  • Thanks for your reply.

    Yes, we have a standalone server. Just for clarification, when I enable circular logging and dismount and mount the database, the 23,000 files should start to disappear - right?

    What's the big disadvantage of enabling circular logging until our backup gets fixed?

    Tuesday, August 7, 2012 3:07 PM
  • Thanks for your reply.

    Yes, we have a standalone server. Just for clarification, when I enable circular logging and dismount and mount the database, the 23,000 files should start to disappear - right?

    What's the big disadvantage of enabling circular logging until our backup gets fixed?

    Yes, they should start to clear.

    But be patient, it may take a bit.

    With circular logging enabled, you can not restore to the point of failure, only to the last full backup.

    Tuesday, August 7, 2012 3:23 PM
    Moderator
  • OK. Theorectically, I could enable circular logging to clear the 23,000 files (approx. 23GB), wait a day or so and then disable once again... then I could restore to the point of failure, right?
    Tuesday, August 7, 2012 3:26 PM
  • No, you will need to do a full backup before any point in time restores are possible.

    Steve


    Tuesday, August 7, 2012 3:34 PM
  • Thanks for both of your feedback. I enabled circular logging, unmounted and mounted the db - all transaction logs disappeared within seconds! 20GB disk space freed up!

    Now we just have to get our backups working. Thanks for your help.

    Tuesday, August 7, 2012 4:42 PM