Oracle DBA terms, explained.

A separately licensed Oracle option that lets a physical standby stay open read-only while redo apply continues.

Database mode in which each filled online redo log is copied to an archived log. Required for Data Guard and for online (hot) backups.

Automatic Storage Management: Oracle's volume manager and file system for database files, which it stores in disk groups such as +DATA and +FRA.

Command-line tool for browsing and managing the files and disk groups in ASM (ls, find, lsdg, cp).

Control utility for Oracle Clusterware and Oracle Restart itself: start or stop the stack and list resource status (crsctl stat res -t).

Oracle's disaster-recovery feature: one or more standby databases are kept in sync with a primary by shipping and applying its redo.

Framework that manages and monitors a Data Guard configuration as a single unit, and runs switchovers and failovers. Used through DGMGRL.

The database name set when the database is created. A primary and all of its standbys share the same DB_NAME.

Name that must differ for every database in a Data Guard configuration. srvctl and the broker identify databases by it, not by DB_NAME.

Command-line interface for the Data Guard broker: create configurations, add databases, check lag, switch over and fail over.

Unplanned role change: a standby becomes the new primary because the original primary is unavailable. Some data loss is possible, depending on the protection mode.

Fast Recovery Area: a disk location, often an ASM disk group, where Oracle keeps backups, archived logs and flashback logs, and manages their space.

Oracle software that provides Clusterware and ASM. On a single server it runs as Oracle Restart.

Oracle Net process that accepts incoming client connections and hands them to the right database service. Configured in listener.ora.

Configuration file for the Oracle Net listener: addresses it listens on and, optionally, statically registered services.

Initialization parameters that say where redo is archived: locally (LOCATION=) or to a standby database (SERVICE=).

Managed Recovery Process: the background process on a physical standby that applies the redo received from the primary.

Oracle's tool for applying and listing patches (interim patches and Release Updates) in an Oracle home.

Single-server version of Grid Infrastructure that automatically restarts registered resources (ASM, listener, databases) after a failure or reboot.

Top-level directory for Oracle software and diagnostic files. Oracle homes are usually installed beneath it.

Directory where one Oracle software release is installed: binaries, libraries and network configuration. Tools use the environment variable to find them.

Name of the database instance on this server. The environment variable tells tools such as SQL*Plus which local instance to connect to.

A block-for-block copy of the primary database, kept current by applying the primary's redo (Redo Apply).

Process Monitor background process. An ora_pmon_<SID> process in ps output shows that the instance is running.

Real Application Clusters: several instances on different servers open the same database at the same time, for scalability and availability.

Recovery Manager: Oracle's tool for backup, restore and recovery, and for creating standbys with DUPLICATE ... FOR STANDBY.

Single Client Access Name: one cluster-wide host name that clients use to connect to a RAC database, whichever nodes are up.

Server parameter file: the binary initialization parameter file an instance reads at startup. ALTER SYSTEM ... SCOPE=SPFILE or BOTH writes to it.

Oracle's command-line tool for running SQL, PL/SQL and administration commands such as STARTUP and SHUTDOWN.

Server Control utility: registers databases, listeners and ASM with Oracle Clusterware or Oracle Restart, and starts, stops and configures them.

Redo log files on the standby that receive redo from the primary as it is generated, so it can be applied in real time.

Planned role reversal between the primary and a standby, with no data loss. Used for maintenance and DR testing.

Oracle Net file that maps connect identifiers (net service names) to listener addresses and service names.