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

I have set up my file system policy to allow:
“elasticfilesystem:ClientMount”,
“elasticfilesystem:ClientWrite”,
“elasticfilesystem:ClientRootAccess”
and likewise for my iam policy for the user role of my sagemaker user.

From what I have read online, there are two potential reasons:

1. My fs is read-only: https://repost.aws/knowledge-center/efs-enable-read-write-access
2. I am missing some kind of posix permissions. It is commonly resolved through something like an access point: https://docs.aws.amazon.com/AmazonS3/latest/userguide/access-points.html

Does anyone have any idea how to resolve this? Are my hypotheses correct? Unsure why following the instructions does not work. I don’t see a way to mount an access point on to sagemaker studio, for example.