Volume names must be a minimum of 2 characters in length
This is a Docker client limitation. The client will interpret a single character name as being a Windows path. See bug 25773.
Because Docker Swarm does not orchestrate volume creation across multiple nodes, only the ontap-nas and ontap-san drivers will work in Swarm.
If a FlexGroup is in the process of being provisioned, ONTAP will not provision a second FlexGroup if the second FlexGroup has one or more aggregates in common with the FlexGroup being provisioned.