how to import a downloaded BTC blockchain into Bitcoin Core

Hey everyone I'm trying to set up a BTC node on my Mac, but my internet plan can't handle downloading the entire blockchain (720 GB) all at once... So, I'm thinking of asking a friend to download the BTC blockchain on his Windows PC for me (no worries about security, it'll be all good). My question is: can I easily import this blockchain that my friend downloaded into my Bitcoin Core app from an external hard drive and then just start syncing from that point?

Hlw Hey there mate! Yes, you can afaik. Another user made the same query in the this board! And this is what NotATether suggested earlier in that thread. You should give it a try and I believe it would fix that problem of yours with Bitcore core and the internet! Quoting it here again for better visibility, in case u missed it! Hope that helps!

This is the wrong mindset for Bitcoin. The proper way would be to copy the data, download your own version of Bitcoin Core, and let it rescan the entire blockchain to make sure it's correct. You'll still need to download 1+ GB per week to keep your blockchain synced.

This can only work for Windows ==> Windows PC. It wouldn't work for Windows ==> Mac PC, the dir on Mac isn't the same with windows. The best he can do is copy the Bitcoin folder and replace it with the one on his Mac Bitcoin core directory. I don't support this though, always verify don't trust.

Another option could be to connect both computers to the same local network, and manually add the other node in Bitcoin Core so they can sync locally. Note: I've never tried this but it should be possible.

thanx, i will have a look thank you very much, I couldn't figure it out by myself, unfortunately I don't have enough space in my main hd too... do you believe I can still go to the bitcoin core settings and change path (to external hd) ? otherwise I will have to reconsider my plan.. appreciate all your support and explanations guys thx

That's possible, but I wouldn't do it: external disks sometimes disconnect when you touch the cable. That would corrupt your block data. Taking a step back: what's the reason you want to run a full Bitcoin node? If you have neither the required disk space, nor the bandwidth, why not use a light wallet such as Electrum? Or solve the disk space problem by pruning the blockchain, unless you have a reason to need the full chain.

thanks for helping me taking a step back, I'm new to bitcoin from a technological point of view I want to protect my transactions (tx), so I've heard that one of the best habit is to use its own server to protect its address and accounts from public information Yes, my goal is to use pruning blockchain but I guess I still have to download the full blockchain at least once before the pruned node keep only the last ones.. (like 2 go) I didn't know about light wallet such as Electrum, I will do some research to know if it can do the job I want -- EDIT : I've just read the Electrum documentation : "The client subscribes to its own addresses (nit: sha256 hashes of scriptPubKeys) so that it would be notified of new transactions touching them. It also synchronizes the existing history of its addresses. This means the client sacrifices some privacy to the server, as the server can now reasonably guess that all these addresses belong to the same entity."  also later  : "Further, all of the connected servers will see the client’s IP address (which might be that of a proxy/VPN/Tor, if used)" --> so it won't fit with my need for privacy My idea is to have : pruned node + sparrow that's my plan, but I guess I need to download the 720 Go first before to rune the pruned node option

When you say "protect", do you mean protect against theft or protect your privacy? You could use Electrum over Tor. That still means the server can know which addresses belong to the same wallet, but it doesn't know who and where you are. If you set Bitcoin Core to prune when you first start it, it will prune on the fly. So if you prune to the minimum (550 MB blocks), it won't take more than ~15 GB in disk space (my current chainstate takes 12 GB). But syncing a pruned node is just as demanding as syncing a full node (in terms CPU, bandwidth, RAM and disk activity), so it takes a while. Bitcoin Core is indeed more private, especially if you run it over VPN/Tor. Plus hardware wallet? Depending on how much you're going to store, it's good practice to think about safety from the start.

" When you say "protect", do you mean protect against theft or protect your privacy? You could use Electrum over Tor. That still means the server can know which addresses belong to the same wallet, but it doesn't know who and where you are." --> yes, about privacy, thanks for those precision, although I don't really know how "knowing which addresses belong to the same wallet" would be harmful or not "If you set Bitcoin Core to prune when you first start it, it will prune on the fly. So if you prune to the minimum (550 MB blocks), it won't take more than ~15 GB in disk space (my current chainstate takes 12 GB). But syncing a pruned node is just as demanding as syncing a full node (in terms CPU, bandwidth, RAM and disk activity), so it takes a while." --> didn't know that, on the fly space is 12 GB but data download has to be 720 Go anyway, isn't it ? And how much Go is the blockchain update by month, once first pruned is ok, is it ike 10 Go new data download ? "Bitcoin Core is indeed more private, especially if you run it over VPN/Tor." --> will try my best to go for it "Plus hardware wallet? Depending on how much you're going to store, it's good practice to think about safety from the start." --> you right, my complete set up would be : AirGap wallet + pruned node + Sparrow Have you heard about AirGap ? I found it to be the best solution ever lol, and want to get rid about ledger hw (although it is said you can use personal node to convey tx)

My usual anser is: "it depends". If you want to be absolutely sure no chain analysis company can access this data, you shouldn't use a public Electrum server. But considering Electrum's popularity, I don't think that's a concern to most people. When you use Bitcoin Core, you can also reduce your privacy by linking different addresses together on-chain. Correct. I think it's about 1-2 GB download per week. But if you allow incoming connections so your node is also uploading, you can transfer much more data. As always, privacy comes at a cost. I wouldn't do it with less than 16 GB RAM, and memory consumption only gets worse in the future. A quick search shows it's "an offline phone". I wouldn't risk my money on that.

Ok thx, I will weigh the pros and cons Ok thx, It gives me an idea Yes, although I'm not planning to run the node continuously (I know it would be better for the btc ecosystem / community) Why not ? I mean the main question re security is having your key offline, isn't it ? What would be your top 3 in terms of hardware wallet / storage ?

I don't trust phones. Even when offline they can still be connecting things like "find my phone". It's something I can't control, unlike an offline Linux PC. Here too: "it depends". A Trezor hardware wallet (connected to Electrum) is one of the best combinations of security and ease of use. Bitcoin Core is much harder to use offline. But, depending on the amount, a mobile phone wallet (Mycelium, Unstoppable Wallet, Coinomi, Blue Wallet and more) can also be very convenient to pay on the road, while offline air-gapped cold storage is safer for long-term storage. I use different wallets for different purposes. To start, it doesn't hurt to familiarize yourself with different wallets.

"I don't trust phones. Even when offline they can still be connecting things like "find my phone". It's something I can't control, unlike an offline Linux PC." --> I guess apple os are unix based, the find my phone can be switched off from the software, but ok I get the point Ok thank you for the talk and advices, appreciate !