Has anybody tried to run PoA networks with 100 or more validators? Given a fixed block size, how did the number of validators effect transaction throughput and latency?
1 Answer
This paper addresses detail comparison of Aura, Clique and PBFT.
The key difference in terms of latency according to this paper is :
In Aura, each block proposal requires two message rounds: in the first round the leader sends the proposed block to all the other authorities, in the second round each authority sends the received block to all the other authorities. A block is committed after a majority of authorities have proposed their blocks, hence the latency in terms of message rounds in Aura is 2( N/ 2 + 1), where N is the number of authorities. In Clique, a block proposal consists of a single round, where the leader sends the new block to all the other authorities. The block is committed straight away, hence the latency in terms of message rounds in Clique is 1. Such a huge difference between Aura and Clique is due to their different strategies to cope with malicious authorities aiming at creating forks: Aura waits that enough other blocks have been proposed before committing, Clique commits immediately and copes with possible forks after they occur. Clique seems to outperform PBFT too, which takes three message rounds to commit a block.
So the number of authorities has a linear relationship with the latency (in terms of message rounds)in case of Aura. If the number of authorities increases the latency (in terms of message rounds) will increase.
On the other hand latency(in terms of message rounds) remains unaffected by the number of authorities.
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2Please elaborate on some of the key points in the link within your answer. A link only answer can be subject to losing its value for future visitors if the link breaks, and it is better to share the main details in your answer. Sep 11, 2018 at 8:06
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Thank you @RaghavSood! Just to be sure I got it right, a message round takes in average as long as the block time, right? So if the block time is set to 5 sec and there are 100 validators, Aura would commit a particular block 500 seconds after the block was proposed. Clique would commit the block within 5 sec but with no guarantee regarding finality. But what about the communication overhead? Having 100 validators in Aura means approx. N^2 messages for a single block. Is it feasible to have 100, 1000 or even more validators?– zofaSep 11, 2018 at 13:55
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1Yes, I agree with you. I think it is not feasible to have a large number of validators(authorities). The number of validators(authorities) shall be restricted if a blockchain network is using Aura consensus algorithm. Sep 12, 2018 at 7:19
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1have a look at this question as well ethereum.stackexchange.com/questions/58521/… Sep 12, 2018 at 10:51