SageMaker AI environment variables and the default paths for training storage locations
The following table summarizes the input and output paths for training datasets, checkpoints, model artifacts, and outputs, managed by the SageMaker training platform.
| Local path in SageMaker training instance | SageMaker AI environment variable | Purpose | Read from S3 during start | Read from S3 during Spot-restart | Writes to S3 during training | Writes to S3 when job is terminated | 
|---|---|---|---|---|---|---|
| 
               
  | 
            
               SM_CHANNEL_  | 
            
               Reading training data from the input channels specified through the SageMaker AI Python
                SDK Estimator  | 
            Yes | Yes | No | No | 
| 
               
  | 
            SM_OUTPUT_DIR | 
               Saving outputs such as loss, accuracy, intermediate layers, weights, gradients,
                bias, and TensorBoard-compatible outputs. You can also save any arbitrary output
                you’d like using this path. Note that this is a different path from the one for
                storing the final model artifact   | 
            No | No | No | Yes | 
| 
               
  | 
            SM_MODEL_DIR | 
               Storing the final model artifact. This is also the path from where the model artifact is deployed for Real-time inference in SageMaker AI Hosting.  | 
            No | No | No | Yes | 
| 
               
  | 
            - | 
               Saving model checkpoints (the state of model) to resume training from a certain point, and recover from unexpected or Managed Spot Training interruptions.  | 
            Yes | Yes | Yes | No | 
| 
               
  | 
            SAGEMAKER_SUBMIT_DIRECTORY | 
               Copying training scripts, additional libraries, and dependencies.  | 
            Yes | Yes | No | No | 
| 
               
  | 
            - | 
               Reading or writing to   | 
            No | No | No | No | 
1
      channel_name is the place to specify user-defined channel names for training data
      inputs. Each training job can contain several data input channels. You can specify up to 20
      training input channels per training job. Note that the data downloading time from the data
      channels is counted to the billable time. For more information about data input paths, see
        How Amazon SageMaker AI
        Provides Training Information. Also, there are three types of data input modes that
      SageMaker AI supports: file, FastFile, and pipe mode. To learn more about the data input modes for
      training in SageMaker AI, see Access Training
      Data.
2 SageMaker AI compresses and writes training artifacts to TAR files
        (tar.gz). Compression and uploading time is counted to the billable time. For
      more information, see How Amazon SageMaker AI Processes
        Training Output.
3 SageMaker AI compresses and writes the final model artifact to a TAR
      file (tar.gz). Compression and uploading time is counted to the billable time.
      For more information, see How Amazon SageMaker AI Processes
        Training Output.
4 Sync with Amazon S3 during training. Write as is without compressing to TAR files. For more information, see Use Checkpoints in Amazon SageMaker AI.