Function of OCR Master Node OCR master is in charge of OCR update and is the only one that's allowed to update, the post shows a way to find OCR master. 1. The default OCR master is always the first node that's started in the cluster. 2. When OCR master (crsd.bin process) stops or restarts for whatever reason, the crsd.bin on surviving node with lowest node number will become new OCR master. Finding OCR Master Node The following method can be used to find OCR master: 1. By … [Read more...] about How to Find OCR Master Node
RAC
Script To Find Redolog Switch History And Find Archivelog Size For Each Instances In Oracle RAC
This script will list the below items from each instance in the RAC Database. Report the redo log switches on an hourly basis from the all the instances on RAC Database Report the size of the archive logs generated on daily basis from all the instances on RAC Database The same can be used for a Standalone (Non-RAC) Database as well. The script Here is the actual script: /* setting up the environment */ set linesize 200 pagesize 1000 column day format a3 column total format … [Read more...] about Script To Find Redolog Switch History And Find Archivelog Size For Each Instances In Oracle RAC
Recommendation for the Oracle Real Application Cluster Interconnect and Jumbo Frames
Introduction This post points out the issues surrounding Ethernet Jumbo Frame usage for the Oracle Real Application Cluster (RAC) Interconnect. In Oracle Real Application Clusters, the Cluster Interconnect is designed to run on a dedicated, or stand-alone network. The Interconnect is designed to carry the communication between the nodes in the Cluster needed to check for the Clusters condition and to synchronize the various memory caches used by the database. Ethernet is a widely used … [Read more...] about Recommendation for the Oracle Real Application Cluster Interconnect and Jumbo Frames
IPv4 Subnet Basics and Oracle Clusterware
What's IPv4 Subnet The IP subnet is a logical separation of IP addresses bounded by the subnet mask. The first address is used as the Subnet Identification (subnet ID or subnet number or route definition) while the last is the broadcast address. For example, subnet ID 10.1.0.0 and netmask 255.255.255.128 produces an IP range of 10.1.0.0 - 10.1.0.127. In this range, 10.1.0.0 is the subnet ID and 10.1.0.127 is the broadcast address. Changing the netmask to 255.255.254.0, the IP range will be … [Read more...] about IPv4 Subnet Basics and Oracle Clusterware
Oracle RAC instabilities due to firewall (netfilter/iptables) enabled on the cluster interconnect
Oracle Clusterware may not startup (root.sh on second node fails with "Failure at final check of Oracle CRS stack."), due to a firewall (such as iptables on Linux) configured on the cluster interconnect. Other symptoms include moderate to serious performance and stability issues, directly related to such firewalls. Examples are false evictions of nodes, 'IPC SEND/RECEIVE TIMEOUT' and slow/uneven performance. Oracle RAC uses the cluster interconnect to send buffer cache blocks between … [Read more...] about Oracle RAC instabilities due to firewall (netfilter/iptables) enabled on the cluster interconnect
Difference between using srvctl vs using sqlplus for start/stop one or more Oracle Database Instances
The Problem We have had some instances where it seemed that starting rac databases through sqlplus caused performance issues (high load on database server ). Restarting the nodes using srvctl seemed to resolve the performance issue. "Is there any difference between using srvctl vs using sqlplus for starting or stopping one or more database nodes."? The Solution The Differences between SQLPLUS and SRVCTL There are some differences between the use of SQLPLUS and SRVCTL utilities. - Both … [Read more...] about Difference between using srvctl vs using sqlplus for start/stop one or more Oracle Database Instances
How To Change Timezone for Oracle Grid Infrastructure
This post illustrates how to change timezone setting for Grid Infrastructure after installation. Note: To check the current time zone on Linux, use the command: "timedatectl | grep 'Time zone'" To check the current time zone on Windows, use the command: "systeminfo | findstr /C:"Time Zone"" Grid Time Zone Setting Once OS default timezone is changed, make sure: For 11.2.0.1, shell environment variable TZ is set correctly for grid user and root. For 11.2.0.2 and above, TZ entry in … [Read more...] about How To Change Timezone for Oracle Grid Infrastructure
What is OCFS or OCFS2
1. What is OCFS for Linux? OCFS is an open source clustered file system for Linux designed for use with Oracle RAC on Linux to store Oracle datafiles, redo logs, archive logs, voting disks, quorum files and control files. It is NOT a general purpose file system and should not be used to store a shared Oracle home. OCFS, also referred to as OCFS (Release 1), works with the 2.4 version and later of the Linux Kernel like RHEL, CentOS, SUSE. 2. What is OCFS2 for Linux? OCFS2 is the next … [Read more...] about What is OCFS or OCFS2
How to Failover a Service During Instance Shutdown Using SRVCTL
This post explains the option of srvctl to failover the service when we stop the instance. Normally Clusterware doesn't failover any of the resources during a planned shutdown. The failover will work during unplanned outages and any srvctl shutdown is basically a planned shutdown from a Clusterware point of view. The -f option of srvctl would failover the running services to another instance, before shutting down the instance. Usage: srvctl stop instance -d [db_unique_name] {-n [node_name] … [Read more...] about How to Failover a Service During Instance Shutdown Using SRVCTL
How to change the SCAN IP address (SCAN VIP resources) in 11gR2 Grid (CRS) environment
The IP addresses associated with the SCAN VIP resources are initially set when the SCAN resources are created. Any changes to the DNS entry for the SCAN are not automatically propagated to the clusterware and need to be done manually. This applies only to installations that are not using GNS. The information in this note can also be helpful in cases where SCAN was originally configured with just one address and is now being expanded to accommodate three IP addresses. Below is an example using … [Read more...] about How to change the SCAN IP address (SCAN VIP resources) in 11gR2 Grid (CRS) environment