Everything `geth` persists gets written inside its data directory (except for the PoW Ethash DAG, see note below).
The default data directory locations are platform specific:
* Mac: `~/Library/Ethereum`
* Linux: `~/.ethereum`
* Windows: `%APPDATA%\Ethereum`
Accounts are stored in the `keystore` subdirectory. The contents of this directories should be transportable between nodes, platforms, implementations (C++, Go, Python).
To configure the location of the data directory, the `--datadir` parameter can be specified. See [CLI Options](../interface/command-line-options) for more details.
_**note:** the [ethash dag](../legacy/mining) is stored at `~/.ethash` (Mac/Linux) or `%APPDATA%\Ethash` (Windows) so that it can be reused by all clients. You can store this in a different location by using a symbolic link._
Sometimes the internal database formats need updating (for example, when upgrade from before 0.9.20). This can be run with the following command (geth should not be otherwise running):
```
geth upgradedb
```
## Cleanup
Geth's blockchain and state databases can be removed with:
```
geth removedb
```
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.
## Blockchain import/export
Export the blockchain in binary format with:
```
geth export <filename>
```
Or if you want to back up portions of the chain over time, a first and last block can be specified. For example, to back up the first epoch:
```
geth export <filename> 0 29999
```
Note that when backing up a partial chain, the file will be appended rather than truncated.
Import binary-format blockchain exports with:
```
geth import <filename>
```
_See https://github.com/ethereum/wiki/wiki/Blockchain-import-export for more info_
And finally: **DO NOT FORGET YOUR PASSWORD** and **BACKUP YOUR KEYSTORE**