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# Backup Tool

## 1. Overview

The IoTDB Full Backup Tool is designed to create a full backup of a single IoTDB node’s data via hard links to a specified local directory. The backup can then be directly started and joined to the original cluster. The tool offers two modes: **Quick Mirror Mode** and **Manual Backup Path Mode**.

> **Notes**:
>
> * **Stop the IoTDB service before starting the backup**.
> * The script runs in the background by default, and logs are saved to log files during execution.


## 2. Backup Modes

### 2.1 Mode 1: Quick Mirror Mode

#### Usage

```bash
backup.sh/backup.bat -quick -node xxx 
# Optional values for xxx are shown in the following examples

backup.sh/backup.bat -quick -node 
# Back up all nodes to the default path 

backup.sh/backup.bat -quick -node all 
# Back up all nodes to the default path 

backup.sh/backup.bat -quick -node confignode 
# Back up only the ConfigNode to the default path 

backup.sh/backup.bat -quick -node datanode 
# Back up only the DataNode to the default path
```

#### Parameter Descriptions

| **Parameter** | **Description**                                                                                                                                                                                                                             | **Required** |
| ----------------------- |---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| ---------------------- |
| `-quick`          | Enables Quick Mirror Mode.                                                                                                                                                                                                                  | No                   |
| `-node`           | Specifies the node type to back up. Options: `all`, `datanode`, or `confignode`. Default: `all`. <br>`all`: Back up both DataNode and ConfigNode. <br>`datanode`: Back up only the DataNode. <br>`confignode`: Back up only the ConfigNode. | No                   |

**Process Details**:

1. Check if the `_backup` folder already exists in the current IoTDB directory or paths specified in the configuration file. If it exists, the tool exits with the error: `The backup folder already exists`.
> When the backup folder already exists, you can try the following solutions:
> * Delete the existing _backup folder and retry the backup.
> * Modify the backup path to avoid conflicts.

2. Create hard links from the original `dn_data_dirs` paths to the corresponding `_backup` paths.
    * Example: If `dn_data_dirs=/data/iotdb/data/datanode/data`, the backup data will be stored in `/data/iotdb/data/datanode/data_backup`.
3. Copy other files from the IoTDB directory (e.g., `/data/iotdb`) to the `_backup` path (e.g., `/data/iotdb_backup`).


### 2.2 Mode 2: Manual Backup Path Mode

#### Usage

```bash
backup.sh -node xxx -targetdir xxx -targetdatadir xxx -targetwaldir xxx  
```

#### Parameter Descriptions

| **Parameter** | **Description**                                                                    | **Required** |
| ----------------------- | -------------------------------------------------------------------------------------------- | ---------------------- |
| `-node`           | Node type to back up (`all`, `datanode`, or `confignode`). Default: `all`. | No                   |
| `-targetdir`      | Target directory for backing up the IoTDB folder.                                          | **Yes**      |
| `-targetdatadir`  | Target path for `dn_data_dirs` files. Default: `targetdir/data/datanode/data`.     | No                   |
| `-targetwaldir`   | Target path for `dn_wal_dirs` files. Default: `targetdir/data/datanode/wal`.       | No                   |

**Process Details**:

1. The `-targetdir` parameter is mandatory. If missing, the tool exits with the error: `-targetdir cannot be empty. The backup folder must be specified`.
2. Validate consistency between configuration paths (`dn_data_dirs`, `dn_wal_dirs`) and parameters (`-targetdatadir`, `-targetwaldir`):

    * If `-targetdatadir` or `-targetwaldir` is a single path, it is considered consistent.
    * If the number of source paths (from configuration) does not match the target paths, the tool exits with the error: `-targetdatadir parameter exception: the number of original paths does not match the specified paths`.
3. Check if `-targetdatadir` paths are on the same disk as the original paths:

    * **Same disk**: Attempt to create hard links. If hard links fail, copy files instead.
    * **Different disk**: Copy files directly.
4. Path Matching Rules

* **Many-to-One**: Multiple source paths can be backed up to a single target path.
* **One-to-One**: A single source path can be backed up to a single target path.
* **Many-to-Many**: Multiple source paths can be backed up to multiple target paths, but the pattern must match.

#### Examples

| **Configuration Paths**                                                                       | **`-targetdatadir` Paths**                                                                                                                              | **Result**       |
| ------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------- | -------------------------- |
| `/data/iotdb/data/datanode/data`                                                                  | `/data/iotdb_backup/data/datanode/data`                                                                                                                   |**Consistent**   |
| `/data/iotdb/data/datanode/data`                                                                  | `/data/iotdb_backup/data/datanode/data1,/data/iotdb_backup/data/datanode/data2`                                                                           | **Inconsistent** |
| `/data/iotdb/data/datanode/data1,/data/iotdb/data/datanode/data2`                                 | `/data/iotdb_backup/data/datanode/data`                                                                                                                   | **Consistent**   |
| `/data/iotdb/data/datanode/data1,/data/iotdb/data/datanode/data2`                                 | `/data/iotdb_backup/data/datanode/data3,/data/iotdb_backup/data/datanode/data4`                                                                           | **Consistent**   |
| `/data/iotdb/data/datanode/data1,/data/iotdb/data/datanode/data2;/data/iotdb/data/datanode/data3` | `/data/iotdb_backup/data/datanode/data`                                                                                                                   | **Consistent**   |
| `/data/iotdb/data/datanode/data1,/data/iotdb/data/datanode/data2;/data/iotdb/data/datanode/data3` | `/data/iotdb_backup/data/datanode/data1;/data/iotdb_backup/data/datanode/data1`                                                                           | **Consistent**   |
| `/data/iotdb/data/datanode/data1,/data/iotdb/data/datanode/data2;/data/iotdb/data/datanode/data3` | `/data/iotdb_backup/data/datanode/data1,/data/iotdb_backup/data/datanode/data3;/data/iotdb_backup/data/datanode/data`                                     | **Consistent**   |
| `/data/iotdb/data/datanode/data1,/data/iotdb/data/datanode/data2;/data/iotdb/data/datanode/data3` | `/data/iotdb_backup/data/datanode/data1,/data/iotdb_backup/data/datanode/data3;/data/iotdb_backup/data/datanode/data1,/data/iotdb_backup/data/datanode/data4` | **Inconsistent** |

#### Path Matching Rules Summary

* **Paths separated by `;` only**:
    * `-targetdatadir` can be a single path (no `;` or `,`).
    * `-targetdatadir` can also use `;` to split paths, but the count must match the source paths.
* **Paths separated by `,` only**:
    * `-targetdatadir` can be a single path (no `;` or `,`).
    * `-targetdatadir` can also use `,` to split paths, but the count must match the source paths.
* **Paths with both `;` and `,`**:
    * `-targetdatadir` can be a single path (no `;` or `,`).
    * Split paths first by `;`, then by `,`. The number of paths at each level must match.

> **Note**: The `dn_wal_dirs` parameter (for WAL paths) follows the same rules as `dn_data_dirs`.