As described in the prior post, the shared-disk performance
dilemma is simple:
1. If each node stores/processes data in memory, versus disk, it is much faster.
2. Each node must expose the most recent data to the other nodes, so those other nodes are not using old data.
In other words, #1 above says flush data to disk VERY INFREQUENTLY for better performance, while #2 says flush everything to disk IMMEDIATELY for data consistency.
Oracle recognized this dilemma when they built Oracle Parallel …