Exadata was announced by Larry Ellison at the 2008 Oracle OpenWorld conference in San Francisco for immediate delivery. Let's see what exactly it has which makes it faster and better than Oracle database software.
First of all it's a bundle of hardware and software composed of database servers, Oracle
Exadata Storage Servers, an InfiniBand fabric for storage networking and all the other
components required to host an Oracle Database. The Exadata Storage Server is an integral component of the Exadata Database Machine.
Following are few advanced features of Exadata Server.
- Off load database processing from the database server to storage: As clear from the line in Exadata processing is moved from Database Server to Storage Server and all of this is done in real time. In more simple words:- the data requested by the application is returned rather than all the data in the queried tables.
- Exadata Smart Flash Cache:- The Flash provides intelligent caching of database objects to avoid physical I/O operations and speeds database logging.
- Hybrid Columnar Compression: - Exadata typically provides 10x, and higher, levels of data compression.
The Exadata Storage Server (Exadata storage or Exadata cells) is used as the storage for the Oracle Database in the Database Machine. It runs the Exadata Storage Server Software that provides the unique and powerful features discussed above. The Database Machine is a pre-configured system ready to be turned on day one.
Exadata Database Machine Architecture
In the figure below is a simplified schematic of a typical Database Machine deployment. Two Oracle Databases, one Real Application Clusters (RAC) database deployed across three database servers and one single-instance database deployed on the remaining database server, are shown. (Of course all four database servers could be used for a single four node RAC cluster.) The RAC database might be a production database and the single-instance database might be for test and development. Both databases are sharing the seven Exadata cells in the Rack but they would have separate Oracle homes to maintain software independence. All the components for this configuration – database servers, Exadata cells,InfiniBand switches and other support hardware are housed in the Database Machine rack.
The Database Machine uses a state of the art InfiniBand interconnect between the servers and storage. Each database server and Exadata cell has dual port Quad Data Rate (QDR) InfiniBand connectivity for high availability. Each InfiniBand link provides 40 Gigabits of bandwidth –many times higher than traditional storage or server networks.
Further, Oracle's interconnect protocol uses direct data placement (DMA – direct memory access) to ensure very low CPU overhead by directly moving data from the wire to database buffers with no extra data copies being made. The InfiniBand network has the flexibility of a LAN network, with the efficiency of a SAN. By using an InfiniBand network, Oracle ensures that the network will not bottleneck performance. The same InfiniBand network also provides a high performance cluster interconnect for the Oracle Database Real Application Cluster (RAC) nodes.
For more detail about Exadata. Please read this article http://www.oracle.com/technetwork/database/exadata/exadata-technical-whitepaper-134575.pdf