I followed the instructions here: https://docs.aws.amazon.com/sagemaker/latest/dg/domain-custom-efs.html
I am able to get to the point where I am able to, at the start of a Jupyterlab space, see the option to mount a custom efs, mount it, and see it in my space. However, when I try to write to it, such as creating a notebook inside custom-file-systems/efs/fs-0913ccfbff134d519, I get a:
Permission denied: custom-file-systems/efs/fs-0913ccfbff134d519/Untitled.ipynb