# Pastebin 1cGJiI7T
scott@HAtestAug22:/opt/stack/python-cinderclient$ cinder --os-volume-api-version 3.15 help metadata
usage: cinder metadata <volume> <action> <key=value> [<key=value> ...]
                       <key=value> [<key=value> ...]

Sets or deletes volume metadata.

Positional arguments:
  <volume>     Name or ID of volume for which to update metadata.
  <action>     The action. Valid values are "set" or "unset."
  <key=value>  Metadata key and value pair to set or unset. For unset, specify
               only the key.
  <key=value>  Metadata key and value pair to set or unset. For unset, specify
               only the key(s): <key, key> (Supported by API version 3.15 and
               later)