I am well aware of the utility of light-weight clients on a ethereum.
Yet, for a private blockchain, which contains a limited number of users, I find it wrong.
Let's say we have a private blockchain of 30 accounts, in which only 2 or 3 have downloaded the entire blockchain, and the rest are light-weight clients. Won't that be against the basics of blockchain and decentrilized apps which states that a copy of the ledger should be replicated to all nodes ?
Yes, you are absolutely right. The security of a distributed system heavily depends on the amount of nodes that check and confirm a state update. If only very few nodes have the entire state stored and are able to confirm updates, it is very easy to disturb the network.
That`s why the scaling problem is so difficult: We need to push more transactions through, but we can not put too much load on individual nodes or they will go offline and the network will get more and more insecure.
But back to your question: Private blockchains don't necessarily have to be distributed. If a company with 20 branches and 500 employees want's to implement blockchain technology to track parcels in warehouses, they might be well served with one full node per building and 500 light clients in handheld devices. In this case, the blockchain is not distributed but decentralized, that would already be a great step forward in comparison to the old centralized system this fictional company was using.
