All data relating to a specific Geth instance gets written inside a data directory. The default data directory locations are platform specific:
- Mac: `~/Library/Ethereum`
- Linux: `~/.ethereum`
- Windows: `%LOCALAPPDATA%\Ethereum`
Accounts are stored in the `keystore` subdirectory. The contents of this directories should be transportable between nodes, platforms, and client implementations.
To configure the location of the data directory, the `--datadir` parameter can be specified. See [CLI Options](/docs/fundamentals/command-line-options) for more details. There may exist multiple data directories for multiple networks (e.g. a separate directory for Ethereum Mainnet and the Goerli testnet). Each would have subdirectories for their blockchain data and keystore.
It is important to backup the files in the keystore securely. These files are encrypted using an account password. This needs to be securely backed up too. There is no way to decrypt the keys without the password!
This is useful for deleting an old chain and sync'ing to a new one. It only affects data directories that can be re-created on synchronisation and does not touch the keystore. Specifically, passing the `removedb` command with no arguments removes the full node state database, ancient database and light node database (although light nodes are not currently functional for proof-of-stake Ethereum).