Den tors 29 okt. 2020 kl 20:16 skrev Tony Liu <tonyliu0592(a)hotmail.com>om>:
Typically, the number of nodes is 2n+1 to cover n
failures.
It's OK to have 4 nodes, from failure covering POV, it's the same
as 3 nodes. 4 nodes will cover 1 failure. If 2 nodes down, the
cluster is down. It works, just not make much sense.
Well, you can see it the other way around, with 3 configured mons, and only
2 up, you know you have a majority and can go on with writes.
With 4 configured mons and only 2 up, it stops because you get the split
brain scenario. For a 2DC setup with 2 mons at each place, a split is still
fatal.
--
May the most significant bit of your life be positive.