How to resync Geth

A common reason for Geth to fail can be an unexpected shutdown of a validator machine. Geth uses RAM for temporary memory and during a graceful shutdown some important information will be written to disk. However, during an unexpected shutdown, there isn't time to write to disk (e.g. due to a sudden loss of power) so important data is lost. This loss of data leads to a corruption of the chaindata folder, requiring a resync.

• File Locations

• Steps (If the ancient folder exists)

• Steps (If the ancient folder does not exist)

File Locations

• Standard location of the chaindata folder.

  /var/lib/goethereum/geth/chaindata/

• Standard location of the ancient folder.

  /var/lib/goethereum/geth/chaindata/ancient

Steps (If the ancient folder exists)

Good news! The required resync can be made much faster than a full resync simply by keeping the ancient folder. The ancient folder contains files that are not corrupted during an unexpected shutdown.

1. Stop Geth.

2. Move the ancient folder.

   sudo mv /var/lib/goethereum/geth/chaindata/ancient /var/lib/goethereum/geth/

3. Delete the chaindata directory and recreate it.

   sudo rm -rf /var/lib/goethereum/geth/chaindata
   sudo mkdir /var/lib/goethereum/geth/chaindata

4. Move the ancient folder back to the now empty chaindata directory.

   sudo mv /var/lib/goethereum/geth/ancient /var/lib/goethereum/geth/chaindata

5. Change the ownership of the chaindata directory to the Geth user.

   sudo chown -R goeth:goeth /var/lib/goethereum/geth/chaindata
   sudo chmod 755 /var/lib/goethereum/geth/chaindata
   sudo chmod 755 /var/lib/goethereum/geth/chaindata/ancient

6. Start Geth.

Congratulations! You've successfully started a Geth resync 🥳

Steps (If the ancient folder does not exist)

If the ancient folder does not exist, that's not a problem. It just means you will need to resync Geth from scratch, which will take a bit longer.

1. Stop Geth.

2. Delete the chaindata directory and recreate it.

   sudo rm -rf /var/lib/goethereum/geth/chaindata
   sudo mkdir /var/lib/goethereum/geth/chaindata

3. Confirm the ownership and permissions for the chaindata directory are set to the Geth user.

   sudo chown -R goeth:goeth /var/lib/goethereum/geth/chaindata
   sudo chmod 755 /var/lib/goethereum/geth/chaindata

4. Start Geth.

Congratulations! You've successfully started a Geth resync 🥳