How many collators need to be set on the parachain?

Question

Background

our parachain has won the slot and will launch in the future. So, we firstly face the question of how many collators should be setup in our parachain. Here are some of my questions:

Confusing questions:

1. In our fist stage, we use the simple POA consensus. Also, we need to setup our own collators. How many collators should we setup can we ensure our parachain network's security?
2. In the second stage, we may launch a POS mechanism. So, we need to open some seats for the public collators to produce block. The next two question is that how many public collators seats should we provide? Is there a quantitative relationship between the number of our own collators and the number of public collators?
3. About the latency in parachain, the scene is below:
   we set a fixed number of collators accounts in the chainspec. If I setup one collator to maintain the parachain, the latency is very big. But if I setup the whole fix number of collators, the latency will be small. So why is that? And another is that, if one collator has dropped, will my parachain's network will be affected? Also, After we open some public collators seats, if some public collators dropped, will it will affect our network?

Answer 1

First congratulations for winning a slot to launch your parachain.

Unlike validators, collators has nothing to do with security of the network, by being a parachain, the network is by default trustless and decentralized, and a parachain only needs one honest collator to be censorship-resistant. Collators are similar to validators on any other blockchain, but they do not need to provide security guarantees because Polkadot provides those.

The minimal safe ratio of validators per parachain is 5:1. With a sufficiently large set of validators, the randomness of their distribution along with availability and validity will make sure security is on-par.

Your questions are not easy to answer but let me share some resources I think can be useful to help you clarify your doubts and questions with collators.

• You can check more about this in the Polkadot wiki: Collators and Parachains

• An about Availability and Validity in the Polkadot Protocol Specification.

• To go more in deep with the Parachain security check the research from Web3 Foundation.

• The Go-To Overview for developing a Parachain with a section when talked about Para-nomics.

• For testing: parachain-launch is a script that generates a docker compose file allowing you to launch a testnet of multiple blockchain nodes.

• Check the Collator memory profiling. It should be done to analyze memory leaks, identify where memory consumption is happening, define temporary allocations, and investigate excessive memory fragmentation within applications.

And finally I encourage you to see what other parachains are doing:

• Check this Blog in the Polkadot Forum about Determine Collator node minimal performance requirement

• Moonbeam Collator Requierements