Bitcoin Forum

So I basically copied my entire Bitcoin Core folder which was up to date, so I wouldn't need to download the entire blockchain on another computer.
I downloaded the client, ran it once to let it create the folders, closed it, copied the Bitcoin Core folder with the downloaded blockchain and wallet, opened Bitcoin again and it's downloading the blockchain again.... why? At the begining it seemed like it was validating the blocks not actually downloading them, it was going quicker than normal, but right now im at about 1 year ago and it's going so slow, like the usual actual downloading slow. It says "Updating..." when I leave my cursor on top of the loading bar and shows the processed blocks too.
Is this downloading the blockchain again or the validating the blocks?
This is really frustrating, im wasting an entire day trying to sync in already.I hope this works a lot better in the future to incentive people running nodes.

Are you sure it was "downloading" or just "re-checking" the blockchain?

(the latter will be much quicker but will still take some time)

It should be re-validating and possibly reindexing the blocks, but not redownlading them. It might be rebuilding some of the databases. Also, if you are using another wallet, it needs to check the entire blockchain to see if there are any transactions for the addresses in the wallet.

It's not revalidating or reindeixing , i think its downloading again, this is taking freaking forever, my CPU is getting really hot, it's really frustrating as always with Bitcoin qt.
Im using the same wallet, it's the entire same folder....

Help -> Debug Window -> Network Traffic

If its downloading its downloading, if not its just reindexing. I recently had a blackout which currupted the database and it turned out that the old 3 core machine /w mechanical disk takes ~12 hours to reindex.

Depending on your OS there are different folders for the executable and the blockchain files. I know windows has them in seperate folders, linux typically does not.

Okay, i've just realized by looking at the blocks/ folder, that the client is indeed re-downloading everything again (no wonder its taking forever) and here's the weird part: It's re-writting and replacing my backup (the entire blockchain I copied). I realized this because from block blk00000.dat to blk00140.dat the date is today, and from 141 to the latest file, the date is from 2 days ago (the last time I used the wallet in my other computer). Why is it doing this? It's like the client didn't recognize the blk files and started from scratch or something.. weird. The backup folder is from the latest version, same wallet etc.. (again its the entire folder). I don't get this.

Yes, it is downloading. Like I said before, the blk files are recent from 0 to 140 and counting (now 141) and also double confirmed by looking at the Network Traffic window. I have no idea why.

It is actually not redownloading, it is rebuilding the entire database, which needs to open and read the blk files. This is why the timestamp is changing. If it were re-downloading, it would take much much longer.

I am on the blocks folder with the latest file that has today's date and the size of the file is increasing when I press F5, therefore it is not only opening it but re-downloading it. It's taking forever. This can't be verification only.

Then that means you didn't copy over the full blockchain, or you didn't have the full blockchain when you copied it.

You said you copy it 2 days ago and started importing it today. It is possible that it have to also download the blocks that you have missed during the timeframe. Check the logs first.

Again, I have copied the ENTIRE folder, which was actually used 5 days ago and not 2 but whatever, the point is, this thing is re-downloading the blocks and overwriting them. The networks shows download activity, but in case you still don't get it I took pics:

http://s21.postimg.org/y0wb0wg85/block1.png (http://s21.postimg.org/y0wb0wg85/block1.png)

In here you can see the block it was download yesterday before I gave up and went to sleep. As you see, blk00143.dat its not size 130-131, it's 114, which means it's being re-downloaded and overwritten for some stupid reason. Now here's what happened when I started Bitcoin Core again:

http://s21.postimg.org/khfgv7291/block3.png (http://s21.postimg.org/khfgv7291/block3.png)

Here you can see the behaviour. It finished downloading blk00143.dat, so it reached the standard 130-131 mb of full blocks, then it started with the following block blk00144.dat, which is only 16mb.

http://s21.postimg.org/rjdehe5ut/block4.png (http://s21.postimg.org/rjdehe5ut/block4.png)

After I while I F5'd the folder and as you can see, it went from 16 to 81mb... which means it's obviously re-downloading the blocks for some strange reason, and wasting my time as I wait for it. And it goes on:

http://s21.postimg.org/oo0baj1ut/block5.png (http://s21.postimg.org/oo0baj1ut/block5.png)

As you can see here, my latest block from the backup was 5 days ago:

http://s21.postimg.org/gz3gyt1d1/block2.png (http://s21.postimg.org/gz3gyt1d1/block2.png)

Yet on the green bar in the client im still "1 year ago" and updating at snails pace, with 600 MB of received data on the network window since I opened the client today a while ago.
So as you can see, as a conclusion, it's clear that the client is overwriting my backup block per block, re-downloading the entire thing, which is very frustrating, because not only I lost time copying 40 GB from computer A to computer B, now computer B is ignoring the backup and overwriting it.

Thank you for the screenshots, they are rather helpful. This behavior is odd, and it shouldn't happen. I'm sorry, but I can't help you, I have no idea why it is doing that. Your guaranteed solution is to wait for it to finish downloading and indexing, but that will take a very long time.

That is exactly what im doing. I left my Bitcoin Core wallet opened all night, right now im only at "4 weeks ago". It was still an huge waste of time, both because I had to wait to move 40 GB from a HD thats pretty slow to another, and then wait for the whole thing to get downloaded from scratch ignoring my backup. Thats why im still interested to know why this happened and how to avoid it to happen again in the future.