I've got a question about the disks in the cells. Its more of an academical question, not an actual problem..
If you look at the spec-sheet (http://www.oracle.com/technetwork/server-storage/engineered-systems/exadata/exadata-dbmachine-x3-2-ds-1855384.pdf) for the different configurations, the iops/disk works out to around 300IOPS/disk (in the high performance case).
Isn't that a bit high for a SAS disk? I've not seen any numbers that state anymore then ~ 210 iops/disk for a 15K SAS disk.
Now, I'm not a storage/disk expert so my knowledge may just be very dated.