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Introduction RMAN lets you take an incremental backup starting from a specific System Change Number (SCN), which is a different resynchronization approach from the live, network-based RECOVER ... FROM SERVICE method we covered in an earlier post. This SCN-based method backs up to disk first and transfers the files manually, which makes it a better fit when network bandwidth to the standby is limited, when the standby server can't reach the primary's service directly, or when you want a backup file you can hold onto and stage before applying. In this guide, we'll resynchronize a standby whose archive gap is too large for normal redo apply, using an SCN-based incremental backup. Prerequisites Oracle Data Guard should already be configured. Disable Data Guard Broker if it's in use, since Broker will automatically restart managed recovery (MRP) and interfere with the manual steps below. Environment Used in This Guide Server Primary ...

Introduction Oracle database parameters are settings that define how the database operates, influencing memory allocation, resource limits, security, and performance. These parameters are stored in a parameter file, either a text file (PFILE) or a binary file (SPFILE). Understanding how to view, modify, and reason about these parameters correctly is a core DBA skill, since getting the scope or persistence wrong can mean a change silently disappears on the next restart, or worse, requires unplanned downtime to apply. This guide covers how parameters work, how to modify them safely, and how to tell which ones can be changed without a restart. What Parameters Control Parameters are used to: Set limits for the entire database Set limits on database resources Set user or process limits Control the database's behavior and performance Parameter Files PFILE (Parameter File, init[SID].ora ): a plain text file containing initialization parameters. You can edit it directly, b...

Introduction The STANDBY_FILE_MANAGEMENT parameter controls whether datafile additions and deletions on the primary are automatically replicated to the standby. It accepts two values: MANUAL: disables automatic standby file management. Datafile changes on the primary are not automatically reflected on the standby. AUTO: enables automatic standby file management. This is the recommended setting for almost all Data Guard configurations. Scenario On the standby database, STANDBY_FILE_MANAGEMENT was set to MANUAL, either by mistake or for some other reason. After that, new datafiles were added on the primary, and the primary and standby fell out of sync as a result. This guide walks through diagnosing and fixing exactly this situation. Prerequisites Oracle Data Guard should already be configured. To reproduce this scenario for testing, set STANDBY_FILE_MANAGEMENT to MANUAL on the standby and add datafiles on the primary. Environment Used in This Guide ...

Introduction STATSPACK is a performance diagnosis tool available since Oracle8i. It stores snapshots of system statistics over time, giving you a historical baseline to compare against when troubleshooting performance issues, without requiring the licensed Diagnostics and Tuning Packs that AWR normally depends on. This makes it a practical option for Standard Edition environments, where AWR isn't available. This guide walks through configuring and using STATSPACK step by step. Understanding Snapshot Levels Oracle snapshots are moment-in-time collections of database statistics that Oracle continuously tracks internally. STATSPACK can capture these at several levels, each level building on the one below it and collecting progressively more detail, at the cost of slightly more overhead per snapshot. Level Information Collected 0 General performance statistics 5 Additional data: SQL statements ...

Introduction From 12c onwards, Oracle provides the RECOVER ... FROM SERVICE syntax, which lets you resynchronize a standby database directly over the network from the primary, without needing a fresh RMAN backup transferred manually. It significantly reduces the steps compared to a full re-instantiation, since RMAN pulls only what's needed straight from the primary's service. This is especially useful when a standby has fallen too far behind for normal redo apply to catch up, but not so far gone that a complete rebuild is necessary. In this article, we'll walk through recovering an out-of-sync standby using this method. Prerequisites Oracle Data Guard should already be configured between the primary and standby. Disable Data Guard Broker if it's in use, since Broker will automatically restart managed recovery (MRP) and interfere with the manual steps below. Oracle version 12c or later, this syntax isn't available on older releases. Environment Used in T...