Entries by Arsalan

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ORA 600 [kfk_iodone_invalid_buffer] [IO buffer does not pass HARD checks]

The error occurred when switching from MAXIMUM PERFORMANCE to MAXIMUM AVAILABILITY Data Guard mode on an Exadata system. The primary RAC database, running on version 19c, crashed with an ORA-600 error code. The error mentioned that the redo log for group 45, sequence 509, was incorrectly located on DAX storage, causing issues. The incident details […]

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When RAC instance one is opened on 19c, the database hangs

The symptoms include issues such as the ‘ALTER DATABASE OPEN’ process not completing as logged in the alert log file. DIA0 (Hang Manager reports) sessions are also blocked while waiting for ‘gc freelist.’ The hang manager reports instances waiting for ‘cursor: pin S wait on X’ and ‘gc freelist’, which can lead to extended waiting […]

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Oracle Bug 32043701

Bug Description The bug described in Bug 32043701 involves row cache locks for sequences in Real Application Clusters (RAC) due to the S-optimization feature for dc_sequences. This bug creates locks on the data dictionary rows, primarily to serialize changes to the data dictionary and wait for a lock on a data dictionary cache. How to […]

ORA-04091 error

ORA-04091 is an Oracle error code that indicates that a trigger, stored procedure, or package has encountered a mutating table error. This error occurs when a trigger or procedure tries to modify a table that is already being modified by the same transaction. To resolve the ORA-04091 error, you can consider the following approaches: 1. […]

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Oracle “buffer busy waits”

Buffer busy waits occur when multiple processes compete for access to specific blocks in the buffer cache of an Oracle database. In order to address this issue, it is essential to identify which blocks are causing contention and understand the reasons behind it. The most effective solution is to eliminate the root cause of the […]

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Optimizing Oracle Net for Data Guard: Enhancing Network Throughput and Performance #JoelKallmanDay

Oracle Data Guard is a powerful, high-availability solution that ensures Oracle databases’ continuous availability and protection. Optimizing Oracle Net, which handles the network communication between the primary and standby systems, is essential to achieve optimal performance. This article will focus on optimizing Oracle Net for Data Guard by adjusting the TCP send and receive socket […]

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Oracle Database QoS Management Recommendations

If Performance Objectives are not being met, Quality of Service Management makes a recommendation. Each recommendation focuses on improving the highest-ranked Performance Class by exceeding its Performance Objective. Submissions may include changing consumer group mappings – and reprioritizing work within existing resource boundaries. For example, changing consumer group mappings may involve promoting a specific workload […]

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If you require a certain number of backups to be retained, you can set the retention policy based on the redundancy option. This option requires that a specified number of backups be cataloged before any backup is identified as obsolete. The default retention policy has a redundancy of 1, which means that only one backup […]