Full node vs permanode

Question

I would like to clarify the distinction between the pragmatics and incentive of running a full node vs a permanode. Could you comment if my statements correct,and if necessary correct mine to accurately depict the difference between a full node and a permanode?

Full node

A full node is a node that acts as a discovery node allowing transactions sent by light clients to be faster submitted to the rest of the tangle (and thus verified faster). For me, this is beneficial because I can be sure that my full node is running instead of using some other node that might or might not be down.

Furthermore, a full node can save the partial state of the tangle using the transactions that reached it, and does not store transactions after a snapshot.

Permanode

A permanode is a node that keeps all transaction data even after snapshots. This is beneficial for me if I ever need an exact transaction confirming some payment. Here, two questions arise:

1. Why would anyone run a permanode without financial incentive?
2. How do we know to trust permanodes? If there is a set of trusted nodes maintaining the state, how is this different from let's say Ripple?

Answer 1

A full node contains the full data (that is, all transactions) generated after a snapshot.

The benefit is that nodes can have reduced hardware specs. The drawback is that information that resides in transactions is lost after every snapshot, if the transaction is behind (older than) the snapshot, and has no balance on it.

A permanode contains all transactions ever made. Since you can add a message to a transaction, a message of value, you may like it to be accessible at all times. In that case a permanode would offer you that accessibility. It could be your own node ("free"), or one hosted as a service. They'd also be interesting for research as well as to track the origins of the balances.

Answer 2

Regarding incentive for running permanodes, from this meetup, permanodes will be incentivised by pay per query. The issue of whether permanodes can be trusted can be resolved by drawing a parallel with DPoS - in DPoS decentralisation is partly sacrificed to achieve scalability, similarly full nodes represent federated history maintenance for the sake of more storage space. As long as anyone can become a full node, the system is decentralised enough, at least in my opinion.

Answer 3

or it is simply solved with the "Poof of Inclusion", as it is the case with the current update.

In my opinion, a full node or permanode is then largely obsolete

"The Proof of Inclusion shows that a secret, confirmed message is included in a finite set of messages and thus also serves as proof of a payment made, a hash, a transaction, etc."