How to free up Exchange log drive space when it fills up

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There are a couple of instances where I had to free up the log drive on our Exchange server because the drive is full.  This has happened to me multiple times even with alerting setup and do diligence.  There are just some disasters you cannot prevent – like your Marketing or Ebusiness department decided to send 50,000 campaign emails in an hour filling up your Exchange outbound queue and ended up filling up your log drives too.

When the log drive fills up, Exchange will also automatically dismount your mailbox database associated to the log drive to prevent database corruption.

First thing to do when this happens is CALM DOWN and DON’T PANIC!  You can be back up and working again in a matter of seconds.  Tell your boss not to stay behind you and breath on your neck while you resolve the issue :).

Here are the things I normally do when this issue happens:

1.  Login to the Exchange server and locate the checkpoint file in the log drive.  The checkpoint file has an extension of .CHK and normally starts with E0x.

2.  Run eseutil.exe /mk “path\name.chk” to find out what logs are still needed and what can be safely moved/deleted.  In my example below, I ran the command eseutil.exe /mk e04.chk while I am inside the logs directory.  The result will show you the checkpoint or last log that was committed.


3.  Based on the result, all logs previous to the checkpoint can be safely moved/deleted (I don’t recommend deleting just in case you need them back or you overlooked what files are still needed).

If your checkpoint file is e04.chk then your log files will start with e04 followed by 000 and then the checkpoint HEX.

Example:  e040001810F is the checkpoint log

All files starting with e040001810E and older can be safely moved to another location to free up space.

4.  Once the old log files are moved, go back to the Exchange Management Console and mount the mailbox database.  To save your users, you can immediately try to mount the database after freeing up a couple of megabytes on the log drive.   I would already try to mount the database if I see more than 200MB of freed space.  So your users can already login to their mailboxes while you are still freeing up more space.  And that will make the boss happy.

Note:  If you are unable to mount the mailbox database after the cleanup, make sure that the database is not corrupted.   This issue almost never happens but if it does happen to you, you may have to restore from backup or repair the database.

To prevent future issues, first let your Marketing or eBusiness group send the emails by batch if possible.  🙂 Or enable circular logging for the mailbox database which is by default turned ON.  Also, make sure that your Exchange backup is running successfully each night which will also truncate the logs for you.


One thought on “How to free up Exchange log drive space when it fills up

    […] Today, I noticed that one of our logs drives are filling up rapidly.  I was able to move the unused logs to a different drive but the logs continued to grow (check this link on how to move the unused logs […]

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