We implemented custom file storage in Odoo by allowing users to define a local path through system settings. When a document is uploaded, it's saved to the specified path on the server using standard Python file handling:

os.makedirs(storage_path, exist_ok=True)

full_path = os.path.join(storage_path, filename)

with open(full_path, 'wb') as f:

    f.write(base64.b64decode(file_data))(creating copies of uploading documents and storing in new path does not make your server storage less it make double instead of this use below approach)

Instead of creating duplicate copies of documents in our new file path, we can use a separate OCA module called fs_attachment. This module allows us to configure a custom storage path and define which models and fields (document fields) should store files in that path.

Reference: https://apps.odoo.com/apps/modules/16.0/fs_attachment

This ensures documents are stored outside Odoo’s default filestore, giving more control over file organization and backup.
Thank You.