Exadata Hardware Maintenance & Support

When using Exadata, is it mandatory that all/any hardware issues are only supported by Oracle (under the hardware support that the customer may have), or are there certain activities that can be serviced/supported by te customer (ie. user serviceable) as well ?

For example, if monitoring/exachk flags errors or warnings which needs to be validated by having a physical inspection of the hardware, is it absolutely mandatory that Oracle service engineer services that irrespective of the magnitude of the problem ? The reason I ask is to assess whether an Exadata Administrator will ever need physical access to the hardware (from an administration and support perspective) or not.