Explanation/Reference:
Intelligent Data Placement, a feature of ASM that allows placing data in such a way that more frequently accessed data is located close to the periphery of the disk where the access is faster.
The Exadata software is optimally divided between the database servers and Exadata cells. The database servers and Exadata Storage Server Software communicate using the iDB - the Intelligent Database protocol. iDB is implemented in the database kernel and transparently maps database operations to Exadata-enhanced operations. iDB implements a function shipping architecture in addition to the traditional data block shipping provided by the database. iDB is used to ship SQL operations down to the Exadata cells for execution and to return query result sets to the database kernel.
The inter-database I/O allocations are defined within the software in the Exadata cell and managed by the I/O Resource Manager (IORM). The Exadata cell software ensures that inter-database I/O resources are managed and properly allocated within, and between, databases.