Yes, latency and bandwidth are factors that contribute to the reason why a distributed system cannot have all three properties of the CAP theorem. The CAP theorem, also known as Brewer's theorem, states that in a distributed system, it is impossible to guarantee all of the following three properties simultaneously: consistency, availability, and partition tolerance.
Consistency means that all nodes in a distributed system see the same data at the same time. Availability means that every request to the system receives a response, without guaranteeing that it contains the most recent version of the data. Partition tolerance means that the system can continue to function even if communication between nodes is lost or delayed.
Latency and bandwidth impact the ability of a distributed system to maintain consistency and availability. In order to maintain consistency, a system may need to ensure that all nodes have access to the same data at the same time. However, network latency and bandwidth limitations can make it difficult to synchronize data across multiple nodes in real-time, which can lead to inconsistencies.
Similarly, availability can be impacted by network latency and bandwidth. If a node is unable to respond to requests within a certain time frame due to network latency or bandwidth limitations, the system may be unable to maintain availability.
Partition tolerance, on the other hand, is not impacted by network latency and bandwidth. It is a property that relates to the ability of the system to function even if network partitions occur.
Therefore, while latency and bandwidth can impact the consistency and availability properties of a distributed system, they do not directly impact partition tolerance, which is why a distributed system cannot have all three properties of the CAP theorem simultaneously.
Partition tolerance is a property of distributed systems that refers to the ability of a system to continue functioning properly even when network partitions occur. In other words, a partition-tolerant distributed system can maintain availability and consistency even in the presence of network failures or network partitioning events.
The following features of a distributed system can impart partition tolerance:
Replication: A partition-tolerant distributed system must have the ability to replicate data across multiple nodes. By replicating data, the system can continue to function even if some nodes are unavailable due to network partitions.
Consensus algorithms: A partition-tolerant distributed system must use consensus algorithms to ensure that all nodes in the system agree on the state of the system. Consensus algorithms help to maintain consistency and ensure that all nodes have the same view of the data.
Failure detection: A partition-tolerant distributed system must have the ability to detect node failures and network partitions in real-time. This allows the system to adjust its behavior and maintain availability and consistency even in the presence of failures.
Routing algorithms: A partition-tolerant distributed system must use routing algorithms to ensure that messages are delivered to the correct nodes even in the presence of network partitions.
By using these features, a distributed system can maintain partition tolerance and continue functioning properly even in the presence of network failures or partitioning events. However, it is important to note that achieving partition tolerance often requires trade-offs in terms of consistency and availability, as described by the CAP theorem.
I also need to mention Synchrony, which is defined as the enforcing of a definite upper bound on the time of travel for messages. Full synchrony would mean fractions of nanoseconds of time of travel, strong synchrony would be in the small milliseconds latency, and and weak synchrony is anything from a few seconds days.
Proof of Stake systems have strong synchrony, typically under 1 second drift between the small number of nodes in them.
But I need to revise my statement about the proper attribute balance of bitcoin:
Availability in Bitcoin is strong, you can point to the number of replicas as a metric for this, and it's somewhere in the range of 18 and 25 thousand copies of the complete chain, in actively online nodes.
Consistency is weak, probabalistic. You may have idly wondered why everyone says "6 confirmations to clear"... Well, if you say that it's a 50% chance of a fork in the first block, and if you compound that 6 times you get 1/32, or 0.015625 as a decimal fraction.
Forks in Bitcoin tend to happen when multiple new block solutions are found within a short time of each other. Because of the propagation delay, and perhaps compounded by transient latency inbound on the network of the miner of the second block, basically due to the weak synchrony, there is a period of time after a new block is found where multiple solutions can exist, ie, network partitions.
The "heaviest chain wins" rule tends to rapidly resolve the partitions, and this is the secret sauce that makes for Bitcoin's Double Spend protection - because of being a decentralised system, it is difficult to coerce enough nodes to not send a transaction to other nodes, and once a node sees both transactions they make the same decision.
Yeah, so, definitely A and P, and C is what bitcoin's design necessarily trades off to achieve it.
LN is an entirely different beast. The distributed systems part of it is the peer database and channels, and has weak consistency, it's availability is high, really only limited by network conditions and luck. It's partition resistance is very high, since, after all, in the case of executing a payment, literally every other node on the network could be down and it's still settled. LN uses routing and failure detection, two partition tolerancne strategies, where bitcoin uses consensus and replication.
Is latency and bandwidth the reason why a distributed system cannot have all three properties of the CAP theorem?
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What features of a distributed system impart partition tolerance?
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