RAC

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

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 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

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

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

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