I was recently attempting to backup one of our Proxmox VE’s using OpenVZ’s backup tool ‘vzdump’. In the past when using vzdump, a complete backup of a 100GB VE, for example could be obtained in under and hour or so. This time however, after leaving the process running and returning several hours later, the .tar file was a mere 2.3GB in size.

At first I thought that there might be an issue with one or more nodes in the shared storage cluster, so I decided I would direct vzdump to store the .tar file on one of the server’s local partitions instead. Once again I started the backup, returned several hours later, only to find a file similar in size to the previous one.

Next I decided I would attempt to ‘tar up’ the contents of the VE up manually, that combined with the ‘nohup’ command would allow me to find out at what point this whole process was stalling.

As it turns out, I had thousands of files in my ‘/var/spool/postfix/incoming/’ directory on that VE, and although almost every single file in that directory was small, and the overall directly size was not large at all, the result was that file operations inside that folder had come to a screeching halt.

Luckily for me, I knew for a fact that we did not need any of these particular email messages, so I was simply able to delete the ‘incoming’ folder and then recreate it once all the files had been removed, after that, vzdump was once again functioning as expected.