I’ve received this question a number of times: “What do I do when Exchange logs have filled up my C drive causing Exchange to stop working?” The answer to this one is a bit more complicated than “just do X.” Why? First and foremost, there must be a policy in place to clear the Exchange logs, and the policy will be specific to your company. However, the easiest and the cheapest way to clear the logs is to create a scheduled NT Backup job that backs up the Exchange Stores. This will automatically clear the logs, thus clearing up space.

But when the backup job (and log clearing) has been neglected, what do you do? Here are my suggested steps:

  1. Clear enough space to install CCleaner (on a drive other than C if possible). You won’t need much space for this install.
  2. Run CCleaner to clear up as much space as possible on the C drive.
  3. Attempt to run an NT Backup job immediately.

If that NT Backup job will not run, there are two possible reasons why:

  • There is still not enough space on C.
  • Exchange is not running.

Check the services.msc tool to see if Exchange is running. If it is, it’s time to clear out more space. If you can’t find anything that can be deleted, follow these steps very carefully:

  1. Locate the Exchange logs.
  2. Select the oldest log files (be careful to delete only the oldest log files) and delete them.
  3. Empty the Recycle Bin.

If the NT Backup still won’t run, you should continue deleting the oldest log files until you have enough space for it to run. Once you have Exchange back up and running, you should create a scheduled NT Backup job to regularly clean out the Exchange logs.

Caution: This is not a best practice, but I have run into situations with clients where there was no other option, and the described method managed to get their Exchange server back up and running. It’s risky, but sometimes you have to take risks in order to get your clients’ systems running. In an emergency, this method will work.
Ask Jack: If you have a DIY question, email it to me, and I’ll do my best to answer it. (Read guidelines about submitting DIY questions.)