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Comment by wereHamster | Hacker News Reader

Wait what? I thought a full node needed 200GB+… Since when are the requirements so low?

“ It is possible to configure your node to to run in pruned mode in order to reduce storage requirements. This can reduce the disk usage from over 350GB to around 7GB.”

From [1] in the parent.

Ah, so it's 5 (7) GB for a pruned node! That makes sense. But then the comment is inaccurate:

  A Bitcoin full node only takes 5GB of disk space to run, and 256MB of memory.

Should instead read

  A Bitcoin pruned node only takes 5GB of disk space to run, and 256MB of memory.

A full node may still be required for certain use setups (such as when used by lnd – a Lightning Network daemon).

It is definitely possible to run a lightning node using a pruned backend. The official implementation doesn't "support" it, but that is only because some additional thinking is required on the end user's part. It is really just a matter of implementing the code to instruct the backend to get the pruned, but still needed by lnd, transactions - and the work is happening:

https://github.com/lightningnetwork/lnd/pull/5154

The pruned/archival distinction is orthogonal from the full/simplified categorization. A full node that pruned spent transactions is not a contradiction of terms.

Edit: a “full” node is one which fully validates blocks, meaning it checks that blocks meet all of bitcoin’s consensus rules. All data in bitcoin is either validated once the first time it is seen (like witness data), or at most twice (an output and its later spend). Pruned nodes garbage collect this data once it can provably never be referenced again. This does not diminish the nodes ability to check bitcoin’s consensus rules, so it is still a full node.

It is correct in the bitcoin jargon, but it kinda goes against the common usage of "full".

If you have a "full" version that is missing some info, people will be confused.

Full node is an abbreviation of "Fully validating node", which was a term created in contrast to "simplified payment validation" (which basically means perform no validation yourself and trust that the majority of hashpower is being honest due to pressure of other participants validating).

If you define the term "full" like that, then we need a word for a node which stores all the history.

The term is archive node, which has been in use since history pruning was implemented.

Archive node implies non-pruned and txindex enabled?

One thing that made me laugh regarding the Ethereum “archival node” semantics debate was that equivalent functionality (immediate lookup of any transaction by address) in Bitcoin requires an additional index, like ElectrumX. Apparently many of the loudest Bitcoiners would benefit from understanding the distinction between a block explorer and a full node.

no, txindex doesn't do anything network visible at all. It's just a wallet-ish feature.

You only need to store the most recent blocks for security to verify new blocks. 5GB– the minimum Bitcoin Knots, a variant of Bitcoin Core, allows 3 days of blocks. A chain rewrite/51% attack is unlikely to last 3 days because of the probabilistic grantees.

So the state for all addresses ever used fits in those couple gigabytes? Plus of course full state for a few days for longest-chain purposes, like you wrote.

I thought the majority of the hundreds of gigabytes consisted of dormant and throwaway addresses that still have some value on them, but it sounds like I've got the wrong impression and by removing transaction history for empty addresses and other historic block data, it's only a few gigabytes?

Bitcoin nodes only need to work with the state of existing spendable coins.

The need to track previously used stuff in some other systems to prevent transaction replay is a design flaw that Bitcoin avoided.

The vast majority of the blockchain data is digital signatures which you don't need anymore once you've validated them (except to help other people sync up).

Keep in mind most lightning implementations require a full node to function properly.

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