Sharing Bitcoin Core Blockchain Directory via NFS

Optimize Disk Space and Bandwidth by Sharing Bitcoin's Blocks Directory over NFS.

Consider a scenario: you’re running a Bitcoin Core daemon on a remote server, and you want your laptop’s Bitcoin Core Qt app to utilize the same blocks directory, cutting down on disk space and bandwidth usage. Use NFS (over VPN, since NFS does not provide encryption by default). The downside is, each application requires an exclusive access to the directory, so running both bitcoind and Bitcoin Qt simultaneously becomes impossible. You’ll have to pause Bitcoin Core daemon before firing up Bitcoin Qt.

Adjusting the Bitcoin Directory Structure

Let’s take a look at ~/.bitcoin directory structure:

├── blocks
│   ├── blk00000.dat
│   ├── ...
│   └── index
├── chainstate
├── wallets
└── ...

We’re interested in blocks, blocks/index and chainstate. According to Bitcoin data directory layout blocks contains blockchain and this is what we want to share, blocks/index and chainsate contain volatile LevelDB files that we don’t need to share.

We need to change that structure a bit. Let’s move blocks/index directory to one level up (to ~/.bitcoin root):

mv ~/.bitcoin/blocks/index ~/.bitcoin/index

And then create relative (it’s important) symlink to top-level index directory inside blocks:

cd ~/.bitcoin/blocks/
ln -s ../index index

After completing the adjustments, your directory structure should now look like this:

├── blocks
│   └── index -> ../index
├── chainstate
├── index
└── wallets

Additionally, copy the index & chainstate directories, along with all their contents, from the remote server to the machine where you want to mount the share. Ensure you preserve the directory layout, placing both index and chainstate at the root of ~/.bitcoin.

Create & Mount NFS Share

Let’s assume our bitcoind server utilizes /home/bitcoin/.bitcoin to store its data, and its LAN IP address is 192.168.1.1.

Install NFS server (Ubuntu/Debian):

sudo apt install nfs-kernel-server

Create an NFS share by adding the following line to /etc/exports:

/home/bitcoin/.bitcoin/blocks 192.168.1.0/24(rw,sync,no_subtree_check)

Please note that we are only sharing the blocks directory, not the entire ~/.bitcoin.

After updating the configuration, restart the NFS server:

sudo systemctl restart nfs-kernel-server.service

Now, let’s mount the NFS share on your machine:

sudo mount -t nfs 192.168.1.1:/home/bitcoin/.bitcoin/blocks /home/user/.bitcoin/blocks

Remember, you must stop Bitcoin Core daemon on the server before launching Bitcoin Qt on the machine where you’ve mounted the blocks directory. Once done, you can start Bitcoin Qt, and it will seamlessly utilize the blocks from the NFS share.

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