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The problem is that half the servers failing is indistinguishable from a switch connecting two racks being flaky, or anything else which can lead to half the se
by ori_b 10y ago
The problem is that half the servers failing is indistinguishable from a switch connecting two racks being flaky, or anything else which can lead to half the servers being temporarily disconnected from the others.
- f0urtyfive 10y agoWhy wouldn't you use redundant switches rather than n(2) servers?
- ori_b 10y agoWhy would I buy two switches when I can solve the problem in general with a consensus algorithm that handles hosts going away for any reason? Especially since a flaky switch isn't the only issue. Power loss could bring down even redundant backbone switches, but leave communication within the rack going. You could accidentally push a bad routing config and blackhole traffic to a bunch of hosts. You could send out a bad push that intermittently breaks connectivity to some hosts. And so on.
- ketzu 10y agoClassical consensus only solves the problem for up to 33% failure (3f+1 nodes, with f failures), having half of your servers fail can not be done with paxos.