False Backup Drive Full Warning


Jul 13, 2009
We have a managed dedicated server on WHM with a separate HD for backups.

Everyday we receive a couple of emails with the following content
Drive Warning: /dev/sdb1 (/backup) is 86% full
However, the backup drive is only about 50-55% full.

We were told as follows by support:
You are receiving these messages during the backup process itself.
While backing up your files, the server first copies them uncompressed into
the /backup directory, then begins the compression process.

During this time, the drive becomes full enough to generate a warning, but
then, after compression and removal of the uncompressed files, everything
goes back to normal.

Thus, it is nothing to worry about.
I am not too convinced that this is the real cause:
  1. The warnings come 4-5 hours before the backup process starts.
  2. This doesn't happen on other servers (similar disk usage/capacity).
  3. We had a /backup drive of 160 GB on the same server. It really used to
    get 86% full. This was replaced with a 250 GB drive. But still the warnings
  4. With this process backups should have failed on older drive b'coz it
    would get full before backups are completed. But that never happened.

We have checked thru root WHM as well as shell. The backup drive capacity is
reported correctly at 250 GB.

  • Then from where are these warnings coming?
  • Are the backups first copied and then compressed? Sounds unusual to me on
    various counts!


Jul 13, 2009
No one has any idea of what is this? :(

Is this really how cPanel handles backups?


Well-Known Member
May 9, 2008
Have you already configured Incremental Backup with this server? It will prevent compression and also uses less server resources to first compress the backup files. It may be possible that this option is enabled in your second server and hence you are not facing issues with that one.