Oracle Exadata Storage Server is a highly optimized storage server that runs Oracle Exadata System Software to store and access Oracle Database data.

With traditional storage, data is transferred to the database server for processing. In contrast, Oracle Exadata System Software provides database-aware storage services, such as the ability to offload SQL and other database processing from the database server, while remaining transparent to the SQL processing and database applications. Oracle Exadata storage servers process data at the storage level, and pass only what is needed to the database servers.

Oracle Exadata System Software is installed on both the storage servers and the database servers. Oracle Exadata System Software offloads some SQL processing from the database server to the storage servers. Oracle Exadata System Software enables function shipping between the database instance and the underlying storage, in addition to traditional data shipping. Function shipping greatly reduces the amount of data processing that must be done by the database server. Eliminating data transfers and database server workload can greatly benefit query processing operations that often become bandwidth constrained. Eliminating data transfers can also provide a significant benefit to online transaction processing (OLTP) systems that include large batch and report processing operations.

The hardware components of Oracle Exadata System Software are carefully chosen to match the needs of high-performance processing. The Oracle Exadata System Software is optimized to take maximum advantage of the hardware components. Each storage server delivers outstanding processing bandwidth for data stored on disk, often several times better than traditional solutions.

Oracle Exadata storage servers use state-of-the-art RDMA Network Fabric interconnections between servers and storage. Each RDMA Network Fabric link provides bandwidth of 40 Gb/s for InfiniBand Network Fabric or 100 Gb/s for RoCE Network Fabric. Additionally, the interconnection protocol uses direct data placement, also referred to as direct memory access (DMA), to ensure low CPU overhead by directly moving data from the wire to database buffers with no extra copies. The RDMA Network Fabric has the flexibility of a LAN network with the efficiency of a storage area network (SAN). With an RDMA Network Fabric network, Oracle Exadata eliminates network bottlenecks that could reduce performance. This RDMA Network Fabric network also provides a high performance cluster interconnection for Oracle Real Application Clusters (Oracle RAC) servers.

There are several configurations of storage server each configured to maximize some aspect of storage based on your requirements. Each storage server contains persistent storage media, which may be a mixture of hard disk drives (HDDs) and flash devices. High Capacity (HC) storage servers contain HDDs for primary data storage and high-performance flash memory, which is mainly used for caching purposes. Extreme Flash (EF) storage servers are geared towards maximum performance and have an all-flash storage configuration. Extended (XT) storage servers are geared towards extended-capacity applications, such as online data archiving, and contain HDDs only. HC and EF storage servers are also equipped with additional memory for Exadata RDMA Memory Cache (XRMEM cache), which supports high-performance data access using Remote Direct Memory Access (RDMA).

The Oracle Exadata architecture scales efficiently to handle any workload. To improve performance or increase storage capacity, you can add more storage servers (cells) to the configuration. As more storage servers are added, capacity and performance increase linearly. Data is mirrored across storage servers to ensure that the failure of a storage server does not impact data integrity system availability. The scale-out architecture achieves extreme scalability while lowering up-front costs by allowing storage to be purchased incrementally on demand.