Amazon Aurora: Avoiding Distributed Consensus for I/Os, Commits, Membership

What is new and interesting here are the details of how quorum membership changes are dealt with, the notion of heterogeneous quorum set members, and more detail on the use of consistency points and the redo log. Aurora exploits this to set up protection groups with three full segments, which store both redo log records and materialized data blocks, and three tail segments which store just the redo logs. Individual nodes advance a Segment Complete LSN (SCL), representing the latest point in time for which it has received all log records.

Source: blog.acolyer.org