Hey all, over the past year we at HubSpot have invested heavily in the Quotas feature of HBase. We've built it into our internal tooling, and also pushed many contributions to improve it for all HBase users. These features are all available in 2.6.0+.
Ray Mattingly drove most of these improvements, and just published a blog post on our engineering blog about the whys and hows. Please give it a read if you're interested or having resource contention issues. It's a great read, even as someone who already had deep familiarity with Ray's work here. https://product.hubspot.com/blog/hbase-share-resources