Luke Dashjr on Node without Blockchain.

[Ucy]

Luke Dashjr of Core Twitted this few days ago:

"Remember nodes don't need to store any of the blockchain, just download and process it. Once that's done, the data can be discarded." https://mobile.twitter.com/LukeDashjr/status/953565252846850048?p=v


The quote is part of his series of tweets on Bitcoin's Blockchain security. He encouraged more people to run Nodes to help secure Bitcoin Network but said  that the Nodes can be ran without Blockchain. Doesn't really make sense because I thought Node has to contain Blockchain to be considered a Node.
 
Is the quote possible? How can that be done please?  

[HCP]

You simply run the Node in "pruned" mode... it will download ALL the data, but only keeps the last XXX Megs/Gigs (based on your setting).

While it obviously helps keep the storage requirements down, the total bandwidth required is still massive... and can actually be MORE than if you just keep the downloaded data. For instance, if you ever need to "rescan" (ie. after importing a private key) it'll need to redownload EVERYTHING again.

[DooMAD]

You can find the instructions for running a pruned node on bitcoin.org:  https://bitcoin.org/en/full-node#reduce-storage

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 145GB to around 5GB.

Running a node in pruned mode is incompatible with -txindex and -rescan. It also disables the RPC importwallet. Two RPCs that are available and potentially helpful, however, are importprunedfunds and removeprunedfunds.

To enable block pruning set prune=N on the command line or in bitcoin.conf, where N is the number of MiB to allot for raw block and undo data.

A value of 0 disables pruning. The minimal value above 0 is 550. Your wallet is as secure with high values as it is with low ones. Higher values merely ensure that your node will not shut down upon blockchain reorganizations of more than 2 days - which are unlikely to happen in practice. In future releases, a higher value may also help the network as a whole because stored blocks could be served to other nodes.

There are also options to reduce the traffic and the maximum number of connections if bandwidth is still a concern.

[cellard]

You simply run the Node in "pruned" mode... it will download ALL the data, but only keeps the last XXX Megs/Gigs (based on your setting).

While it obviously helps keep the storage requirements down, the total bandwidth required is still massive... and can actually be MORE than if you just keep the downloaded data. For instance, if you ever need to "rescan" (ie. after importing a private key) it'll need to redownload EVERYTHING again.

Yeah, there are many situations in which you will need to query the entire blockchain (everytime you want to access coins from a fork, you could copy-paste your blockchain into the forked client and save time for instance), so if you can afford the space, by all means keep the entire blockchain. At current blocksize, it's growing at a rate that's assumable to keep on your average 2TB harddrive for a long time. The problem is if you want an SSD... then you are going to need to spend a ton of money. mb/$ is still very expensive for SSD. If you want top performance you are going to need an m.2 SSD and I expect around $700 for a 2TB card which I can't even find easily right now.