Procedure to Allocate More Storage to Root Filesystem of a Pod

Problem

• Is it possible to Allocate more storage to the Root Filesystem of a pod?
• How to increase the current root filesystem size for a pod?

Environment

• Platform9 Managed Kubernetes - All Versions
• Docker Storage Driver - DeviceMapper

Answer

• For the cluster setups with DeviceMapper as the Docker Storage Driver, the docker configuration decides the size of container or pod root filesystem.
• The parameter Base Device Size in docker configuration decides the size of each LVM Logical Volume that will be carved from the total backend Storage Space configured for the Docker Storage.
• This Logical Volume then acts as backend disk for the pod or container.
• To change this parameter we need to change the value of this parameter but there are few caveats. This will be an independent change in docker daemon on each cluster node and this might not be consistent across the docker upgrades performed during the cluster upgrade.
• Hence it is advisable to stick to the default size of a pod root filesystem rather than increasing it by allocating more space.