10 ms·
I think what he meant to ask is “Are 4 nodes less reliable than 3?” and I’m pretty sure the answer is “no” despite the other comment implying otherwise. AFAIK,
by NavinF 5y ago
I think what he meant to ask is “Are 4 nodes less reliable than 3?” and I’m pretty sure the answer is “no” despite the other comment implying otherwise. AFAIK, even nodes can hurt latency, but not reliability.
- tick_tock_tick 5y ago“Are 4 nodes less reliable than 3?” The answer is 3 is no less reliable then 4.
- eklavya 5y agoIt depends on the network topology (likelihood not theoretical) but with the amount of split brains I have witnessed, I would say definitely yes, 4 is less reliable than 3.
- mirekrusin 5y agoCounter-intuitively 4 nodes are less reliable than 3 nodes for majority vote systems. Both can tolerate single failed node. However probability of 2nd node failure is 50% higher for 4 node setup than for 3 node setup. That's because 2nd node failure probablity for 4 node system is P(a) + P(b) + P(c) = 3P and for 3 node system is P(a) + P(b) = 2P; it's 3P vs 2P probablity. It's more than 50% overall because similar probability happens for first node failure - it's more likely that one out of 4 nodes will fail than one out of 3. In other words you have to guarantee one more node running without any reliability gains and that guarantee costs reliability.
- Kinrany 5y agoGah, I meant even, not odd! That is, if having an even number of nodes causes problems, you'll have problems every time one of your odd number of nodes goes down!