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How to Tell if the I/O of the Database is Slow (Doc ID 1275596.1)

Last updated on FEBRUARY 28, 2024

Applies to:

Oracle Database Cloud Service - Version N/A and later
Oracle Database - Enterprise Edition - Version and later
Oracle Database - Personal Edition - Version and later
Oracle Database Cloud Schema Service - Version N/A and later
Oracle Database - Standard Edition - Version and later
Information in this document applies to any platform.


This document outlines some of the thresholds whereby RDBMS Support may consider IO to be slow and thus a potential reason for a performance problem. It also looks into how to collect the supporting evidence from the RDBMS perspective. It does not aim to provide diagnostics to understand why the IO is slow nor does it provide any detailed explanation as to why slow IO may be occurring.

If the underlying cause for slow performance is found to be a result of slow IO at the OS level, then the appropriate vendor responsible for the IO subsystem (hardware and software) should be engaged to diagnose and correct the situation.

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In this Document
 Ask Questions, Get Help, And Share Your Experiences With This Article
 What is "Slow"?
 Response time
 Types of IO
 Read or Write
 Single Block or MultiBlock
 Synchronous or Asynchronous.
 Expected thresholds for response time
 Changes in 19.15 for cell single block physical read waits
 IO Wait Outliers (Intermittent Short IO Delays)
 Identifying  IO Response Time
 Sources in Oracle identifying Response Time 
 10046 Trace File
 System State Dump
 Statspack and AWR reports
 Discuss Troubleshooting I/O Contention

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