creating a backup of blockchain and index #19487

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I changed my external hdd enclosure for an hdd which was storing bitcoin data directory and bitcoind said chainstate was corrupted upon restart. I had rsynced bitcoin data directory to try and back it up in the past while bitcoind was running and restoring that copy didnt work either. So I had to -reindex-chainstate which took 3 days.

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Some way to backup the bitcoin data directory "live", without having to stop bitcoind.

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rsynced the directory while its running and starting bitcoind from that copy didnt work.

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@3ntranced It's an important issue but will take a while to implement. In the meantime: I backup the Bitcoin blockchain (on Ubuntu Linux) without stopping bitcoind every month on my server (basically) like this:

bitcoin-0.20.0/src/bitcoin-cli savemempool
rsync -L --delete -av ".bitcoin/" /media/external/.bitcoin
rsync -L --delete -av ".bitcoin/" /media/external/.bitcoin
rsync -L --delete -av ".bitcoin/" /media/external/.bitcoin
rsync -L --delete -av ".bitcoin/" /media/external/.bitcoin

Usually rsync doesn't do anything anymore for the last 2 executions. I then run bitcoin-qt on a different computer (but you could run it on your server too) like this (connecting only to my own bitcoind): bitcoin-qt -connect=192.168.178.20 -blocksonly=1 -listen=0 -datadir=/media/external/.bitcoin

Bitcoin-qt always repairs the blockchain without problems and this way you'll know if the backup was successful. You can even stop bitcoin-qt cleanly and run it again.

Ok thank you, I ll try to understand and give this a go!

@sumBTC bitcoin-qt -connect=192.168.178.20 -blocksonly=1 -listen=0 -datadir=/media/external/.bitcoin this step is purely to verify the backup correct? if the backup is ok, of course you dont know until you verify, then even if you dont verify, you can rsync the directory back and it will work, right?

this step is purely to verify the backup correct?

To verify and "repair" the blockchain. Before syncing the blockchain, bitcoin-qt will see that bitcoind wasn't shutdown correctly and will first "repair" the blockchain.

In my case, bitcoin-qt never had a problem "repairing" the blockchain so you could skip this step if you want to but it's more risky.

You can always rsync again.

rsync a bunch of times works really well.