How can I back up my node efficiently?

Question

I have two external disks, each with a copy of the Monero blockchain. Most of the time, one of the disks sits in a cupboard and its copy of the blockchain lags behind. Every few days, I plug it in and restart monerod with a suitable argument to --data-dir.

My internet connection is slow, so the efficient way to synchronize my lagging copy against my synchronized copy would surely be something purely local. Perhaps I could run two instances of monerod on the same machine, with settings that cause one of my disks to synchronize against the other; but I don't know what command-line arguments to use. Can someone provide an example?

Or, if there's a better way, what is it? For instance, are there generic computer backup protocols that can update the lagging file by reference to the up-to-date file?

Edit: user36303 has previously provided two good answers to this question. I'm accepting jtgrassie's answer (below) though, because it works using monerod itself, i.e. with no requirement to install anything else.

The downside with that answer is it requires a full copy vs just syncing/copying new blocks. — jtgrassie, Mar 07 '19 at 19:18

score 1 · Accepted Answer · answered Mar 07 '19 at 18:19

Perhaps I could run two instances of monerod on the same machine, with settings that cause one of my disks to synchronize against the other; but I don't know what command-line arguments to use. Can someone provide an example?

If you start a second monerod instance like:

monerod --p2p-bind-port 38080 --rpc-bind-port 38081 --zmq-rpc-bind-port 38082 \
    --no-igd --hide-my-port --p2p-bind-ip 127.0.0.1 \
    --data-dir /path/to/backup/data \
    --add-exclusive-node 127.0.0.1:18080

It will sync it's blockchain from your main, localhost, instance of monerod.

How can I back up my node efficiently?

1 Answers1