# cli.merge_sharded_fsdp_weights – Axolotl

# cli.merge_sharded_fsdp_weights

`cli.merge_sharded_fsdp_weights`

CLI to merge sharded FSDP model checkpoints into a single combined checkpoint.

## Classes

Name | Description
--- | ---
BFloat16CastPlanner | A custom planner to cast tensors to bfloat16 on the fly during loading.

### BFloat16CastPlanner

    cli.merge_sharded_fsdp_weights.BFloat16CastPlanner()

A custom planner to cast tensors to bfloat16 on the fly during loading.

## Functions

Name | Description
--- | ---
do_cli | Parses `axolotl` config, CLI args, and calls `merge_fsdp_weights`.
merge_fsdp_weights | Merge the weights from sharded FSDP model checkpoints into a single combined checkpoint. Should be used if

### do_cli

    cli.merge_sharded_fsdp_weights.do_cli(config=Path('examples/'), **kwargs)

Parses `axolotl` config, CLI args, and calls `merge_fsdp_weights`.

#### Parameters

Name | Type | Description | Default
--- | --- | --- | ---
config | Union[Path, str] | Path to `axolotl` config YAML file. | `Path('examples/')`
kwargs |  | Additional keyword arguments to override config file values. | `{}`

### merge_fsdp_weights

    cli.merge_sharded_fsdp_weights.merge_fsdp_weights(
        checkpoint_dir,
        output_path,
        safe_serialization=False,
        remove_checkpoint_dir=False,
    )

Merge the weights from sharded FSDP model checkpoints into a single combined checkpoint. Should be used if `SHARDED_STATE_DICT` was used for the model. Weights will be saved to `{output_path}/model.safetensors` if `safe_serialization` else `pytorch_model.bin`.

Note: this is a CPU-bound process.

#### Parameters

Name | Type | Description | Default
--- | --- | --- | ---
checkpoint_dir | `str` | The directory containing the FSDP checkpoints (can be either the model or optimizer). | required
output_path | `str` | The path to save the merged checkpoint. | required
safe_serialization | `bool`, optional, defaults to `True` | Whether to save the merged weights with safetensors (recommended). | `False`
remove_checkpoint_dir | `bool`, optional, defaults to `False` | Whether to remove the checkpoint directory after merging. | `False`

#### Raises

Name | Type | Description
--- | --- | ---
| ValueError | If torch version < 2.3.0, or if `checkpoint_dir` does not exist.