# Limitations of customizing Amazon Nova models
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Amazon Nova customization doesn't support the following capabilities on SageMaker.
+ **SSH into the instance to find the metrics**

  Due to security controls in place, you can't SSH into the master node in the training algo-1 instance to find memory stats or NVIDIA stats and validate the training steps.
+ **Support for SageMaker trainer SDK**

  SageMaker trainer is currently not available to start training jobs. You can start training jobs only via **estimator API** today.
+ **Warm pools are not accessible to SageMaker training jobs**

  Due to security controls in place, the SageMaker warm pools can't be used to keep the instance in the warm pool till the time to live.
+ **Custom model merging**

  Merging multiple models is not currently supported. This means that creating multiple LoRA adapters and perform a multi-merge operation with the base model is not available.
+ **Supported observability tool**

  [TensorBoard](https://www.tensorflow.org/tensorboard) is the only supported observability tool to view metrics for SageMaker training jobs. [MLFlow](https://mlflow.org/) or [WandB](https://wandb.ai/site/) are not currently supported. For more information about using TensorBoard in SageMaker, see [TensorBoard in SageMaker](https://docs.aws.amazon.com//sagemaker/latest/dg/tensorboard-on-sagemaker.html).