[PVE-User] vzdump taking long time

[Andreas Heinlein]

Hello,

I am running nightly backups using vzdump on a single node Proxmox 5.1
installation, backing up various VMs and LXC containers. I have one
container (containing an Icinga2 installation) that has a backup size of
1.25 GB and takes almost 2 hours to back up, while another container
running an elasticsearch db has a backup size of 12 GB and takes only 20
minutes to back up.

This is still a test machine, the backup disk is a single external USB
drive - but even that should give ~ 1GB/minute. What could explain the
slow backup of the first container?

Bye,
Andreas