Can we use Docker Storage Driver in loop-lvm Mode on PMK Cluster?

Problem

• Is it possible to setup the PMK cluster with docker storage driver in loop-lvm mode and are there any concerns related to it?

Environment

• Platform9 Managed Kubernetes - All Versions

• Docker

Answer

• For production setups, the device-mapper docker storage driver must be configured to use direct-lvm mode.

• The loop-lvm mode is acceptable only for testing but is not supported for production deployments.

• Frequently loop-lvm mode is preferred over the direct-lvm mode in non-production or testing setups because unlike direct-lvm, it does not need one free block device (a disk or a partition) on the node.

• Although with loop-lvm there is a common and known issue where the the Docker storage gets filled up more frequently due to failure in deletion of the old unwanted data.

• The remedy to this is pruning the docker data manually using the below mentioned command.

Command to prune Docker data

# docker system prune -a -f --volumes

• There is one more and most recommended approach which is to use the Overlay2 as the Docker storage driver in production environment since it is more stable that device-mapper.