On each Exadata storage server, the Exadata System Software contains new Exascale software components, including:
- The Exascale Command-Line Interface (ESCLI) is a command-line administration tool available on Exadata database and storage servers. You can use ESCLI to perform Exascale monitoring and management functions. ESCLI compliments the existing Exadata command-line interfaces (CellCLI and DBMCLI) and does not replace them.
Exascale cluster services, also known as Exascale global services (EGS), provide the core foundation for the Exascale system. EGS primarily manages the storage that is allocated to Exascale storage pools. It also manages storage cluster membership and provides security and identity services for storage servers and Exascale clients. Exascale cluster services use the Raft consensus algorithm. For high availability, EGS runs in a cluster of five service instances. Each EGS instance typically runs on an Exadata storage server. However, for Exadata configurations with fewer than five storage servers, EGS instances run on the Exadata database servers to make up the required number.
Exascale control services, also known as Exascale RESTful Services (ERS), provide a management endpoint for Exascale management operations. All Exascale management operations, including all ESCLI commands, come through ERS. But, no file I/O operations come through ERS.
Exascale vault manager, also known as Exascale data services (EDS), is the collective name for the Exascale software services that manage file and vault metadata:
The system vault manager service (SYSEDS) serves and manages the metadata for Exascale vaults. This metadata includes vault-level access control lists (ACLs) and attributes.
The user vault manager service (USREDS) serves and manages the metadata for files inside the Exascale vaults. This metadata includes file-level access control lists (ACLs) and attributes, along with metadata that defines clones and snapshots. All file control operations, such as open and close, are serviced by the user vault manager service.
The block store manager service (BSM) serves and manages the metadata for Exascale block storage. All block store management operations are serviced by BSM. These operations include creating a volume, attaching a volume, creating a volume snapshot, and so on. BSM also coordinates the block store worker processes.
The block store worker service (BSW) primarily services requests from block store clients and performs the resulting storage server I/O. BSW also plays a role in clone and snapshot creation operations and is responsible for performing volume backup and restore operations.
The instance failure detection (IFD) service is a dedicated lightweight service that quickly detects and responds to any storage server failure. IFD automatically runs on every storage server that is associated with the Exascale cluster.
Apart from EGS, which always runs in a cluster of five service instances, and IFD, which runs on every Exascale storage server. The other Exascale services (ERS, SYSEDS, USREDS, BSM, and BSW) all run multiple instances spread across the available storage servers to provide high availability and share the workload. The exact placement of these Exascale service instances depends on the number of storage servers in the Exascale cluster. Consequently, on a system with only a few storage servers, each will host many different service instances. However, on a system with many storage servers, each might host only a few service instances (possibly none).
Exascale works in conjunction with, and relies on, the core Exadata cell services. Specifically, Exascale requires running instances of Cell Server (CELLSRV), Management Server (MS), and Restart Server (RS) on every storage server.