Looking in the archives, there's an old thread on this topic:
Three important takeaways:
1. From that aspect HBase clusters with less than 9 RegionServers are
not really useful.
2. We have 1ge everywhere so far, and we found this is a single most
bottleneck for write performance.
3. You can store about 2T of effective data per node in HBase, unless
you have a mostly read-only load.
Are these still valid in newer releases?
*If you think you can you can, if you think you can't you're right.*