Component owners are listed in the description field on this Apache HBase JIRA components page. The owners are listed in the 'Description' field rather than in the 'Component Lead' field because the latter only allows us list one individual whereas it is encouraged that components have multiple owners.
Owners are volunteers who are (usually, but not necessarily) expert in their component domain and may have an agenda on how they think their Apache HBase component should evolve.
Duties include:
Owners will try and review patches that land within their component's scope.
If applicable, if an owner has an agenda, they will publish their goals or the design toward which they are driving their component
If you would like to be volunteer as a component owner, just write the dev list and we'll sign you up. Owners do not need to be committers.