Oracle Reference

  APPLIES TO: Oracle Database - Enterprise Edition - Version 11.2.0.1 to 12.1.0.2 [Release 11.2 to 12.1] Solaris Operating System - Version 11.1 to 11.1 [Release 11.0] Oracle Database Cloud Schema Service - Version N/A and later Gen 1 Exadata Cloud at Customer (Oracle Exadata Database Cloud Machine) - Version N/A and later Oracle Cloud Infrastructure - Database Service - Version N/A and later Information in this document applies to any platform. PURPOSE This document is to provide a reference for troubleshooting Clusterware node evictions in versions 11.2 and above.  For clusterware node evictions prior to 11.2, see  Note: 265769.1 SCOPE This document is intended for DBA's and support analysts experiencing clusterware node evictions (reboots). DETAILS NODE EVICTION OVERVIEW The Oracle Clusterware is designed to perform a node eviction by removing one or more nodes from the cluster if some critical problem is detected.  A critical problem could be a node not respondin...

  Wednesday, September 7, 2016 RAC Node Eviction - Why? Who? When? How to diagnose? Why Node Eviction?  OR  Why Split Brain syndrome?  The node eviction/reboot is used for I/O fencing to ensure that writes from I/O capable clients can be cleared avoiding potential corruption scenarios in the event of a network split, node hang, or some other fatal event in clustered environment. By definition, I/O fencing (cluster industry technique) is the isolation of a malfunctioning node from a cluster's shared storage to protect the integrity of data. We want to reboot here as fast as possible. Choosing not to flush local disks or kill off processes gracefully helps us shutdown quickly. It is imperative that we do not flush any IO to the shared disks. Else it may write irrelevant information to clusterware components(OCR or Voting disk) or to database files.  Who evicts/reboot the node? The daemons for Oracle Clusterware (CRS) are started by init when the machine ...

SCAN and VIP Concepts in RAC SCAN NAME  concept was introduced in Oracle 11g and it's still unsolved mystery for few of the  Database Administrators .  The main purpose for using SCAN NAME was to remove each  Cluster  Node entry from Tnsnames.ora file from client machine and to make it more dynamic . Though, Oracle successfully  achieve his goal but make it complicated for newbies or sometimes for experienced DBA's as well. Each term  SCAN NAME, SCAN VIP, SCAN Listener, Node VIP, Local_Listener and Remote_Listener  has its own meaning and role to play in RAC environment. In this post, I will explain meaning and use of each of above discussed Terms. Let's Start with SCAN NAME. SCAN NAME:  SCAN NAME was introduced in Oracle 11g R2 version. This a name which can resolve upto maximum three IP address and minimum one is required for Oracle 11g R2 Real Application Cluster installation. SCAN NAME must be unique in Entire Organization netwo...