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It depends on what you consider "acceptable HA". There are many instances where I'm not trying to protect from a network partition (single data center, monitored batch data loads, etc) and don't have a requirement for that level of tolerance. However, you're right in that it's important to know that nearly every distributed system has edge cases where things might not appear as you thought. Elasticsearch has a section on their Website detailing their resiliency efforts. I wish every company was as transparent about what they're doing on that front so we can all plan and consider expectations better.

Setting up Mongo/Cassandra for HA is still several orders of magnitude less work than with PostgreSQL.

And there are plenty of options for dealing with the issues presented in those series.

Elasticsearch can run with Zookeeper. Zookeeper is pretty solid. Also, MSSQL with AlwaysOn is something which seems very robust too.