Oracle has posted an
on the Sun Oracle Exadata Storage Server that's worth a check.
It's full of interesting bits; the first one that caught my attention was:
Q: Can the Sun Oracle Exadata Storage Server hardware or software be modified or customized?
A: No, customizing or modifying the Sun Exadata Server Hardware or the Oracle Exadata Server Software is not supported. In addition, customers cannot install additional software on the Exadata Storage Servers. If a customer modifies, customizes, or installs additional software on the Exadata Storage Server, then the Oracle Exadata Storage Server Software cannot be supported.