Is there an existing issue for this?

•  I have searched the existing issues

Current Behavior

Any additional PVC is mounted under /opt/app-root/src.
In fact, when you set the mount path to be /data on the dashboard, the storage is mounted under /opt/app-root/src/data in the notebook.
This is an issue when you need to mount specific resources under a different path.
For example, to train with Pytorch with lots of data/resources, you need a supplemental storage space mounted at /dev/shm to increase shared memory. Right now it's feasible only by hacking the Notebook YAML through the OpenShift console.
Right now this is the only way to do serious PyTorch training.

Expected Behavior

You should be able to mound a PVC anywhere in the container filesystem.

Steps To Reproduce

Try to mount a volume, it will always be under /opt/app-root/src.

Workaround (if any)

• Create the additional storage through the dashboard
• Mount it anywhere, e.g. /shm
• Stop the notebook
• With the OpenShift Console, or CLI, edit the corresponding Notebook YAML
• modify the mount point from /opt/app-root/src/shm to /dev/shm
• Restart the notebook. The new configuration is preserved and the volume is mounted where you wanted it