ASP.net Cluster Raft question to configure full in memory mode

[guillaume-chervet]

ASP.net Cluster Raft question to configure full in memory mode

[sakno]

MemoryBasedStateMachine abstract class is for building in-memory current view of the data, but Write-Ahead Log is still persistent. It means that the in-memory state can be recovered from the persisted log entries.
DiskBasedStateMachine is for building complex DB engines such as SQL or document-oriented databases. The difference is fully explained here.

For security reasons, you can use MemoryBasedStateMachine and encrypt log entries stored on the disk. However, it can be done by Linux infrastructure (partition with enabled fs-level encryption) rather than by code. The same true if you want to place a whole WAL to the memory. Just mount ram-fs on your Linux machine and specify a path to that mount point as a storage for WAL. Everything will be in the memory in that case.

However, I strongly discourage from doing that. Persistence is a major characteristics of Raft. Let's imagine you have 7 nodes. Due to failure, 4 of them are down. Due to lack of persistence, they lost any state. On restart, they have a conflict with other 3 nodes because their WALs not empty. The cluster will not be able to reach the majority without human intrusion.