# Configuring SageMaker Debugger to save tensors
<a name="debugger-configure-hook"></a>

**Note**  
Amazon SageMaker Debugger is no longer open to new customers. Existing customers can continue to use the service as normal. AWS continues to invest in security and availability improvements for Debugger, but we do not plan to introduce new features. For more information, see [Debugger availability change](debugger-availability-change.md). 

*Tensors* are data collections of updated parameters from the backward and forward pass of each training iteration. SageMaker Debugger collects the output tensors to analyze the state of a training job. SageMaker Debugger's [`CollectionConfig`](https://sagemaker.readthedocs.io/en/stable/api/training/debugger.html#sagemaker.debugger.CollectionConfig) and [`DebuggerHookConfig`](https://sagemaker.readthedocs.io/en/stable/api/training/debugger.html#sagemaker.debugger.DebuggerHookConfig) API operations provide methods for grouping tensors into *collections* and saving them to a target S3 bucket. The following topics show how to use the `CollectionConfig` and `DebuggerHookConfig` API operations, followed by examples of how to use Debugger hook to save, access, and visualize output tensors.

While constructing a SageMaker AI estimator, activate SageMaker Debugger by specifying the `debugger_hook_config` parameter. The following topics include examples of how to set up the `debugger_hook_config` using the `CollectionConfig` and `DebuggerHookConfig` API operations to pull tensors out of your training jobs and save them.

**Note**  
After properly configured and activated, SageMaker Debugger saves the output tensors in a default S3 bucket, unless otherwise specified. The format of the default S3 bucket URI is `s3://amzn-s3-demo-bucket-sagemaker-<region>-<12digit_account_id>/<training-job-name>/debug-output/`.

**Topics**
+ [Configure tensor collections using the `CollectionConfig` API](debugger-configure-tensor-collections.md)
+ [Configure the `DebuggerHookConfig` API to save tensors](debugger-configure-tensor-hook.md)
+ [Example notebooks and code samples to configure Debugger hook](debugger-save-tensors.md)