Category Archive: RAC

May 18

Increase VOTE diskgroup in ASM for GI 12.2 Upgrade

Oracle 12.2 requires more disk space in your Voting Disk/OCR area than previous versions. In the past, I had a pretty small diskgroup for Vote and OCR. Here are the instructions I followed to setup Oracle RAC on my laptop for 12.1. Before I can upgrade to Grid Infrastruture, I need to add more …

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Feb 23

Oracle RAC on Third-Party Clouds

Yesterday, I came across this white paper from Oracle Corp about Oracle RAC Support on Third-Party Clouds. The paper is definitely a must-read for those who want to run Oracle RAC on AWS, Google or Azure cloud providers. The first paragraph was promising where it stated: Oracle also maintains an open policy for Third-Party Cloud …

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Jun 07

Oracle RAC VIP and ARP Primer

I’ve been running across a number of questions about Virtual IP (VIP) addresses for Oracle RAC lately. I hope this blog post can help shed some light on what a VIP is, how they work, and why Oracle RAC leverages them. Before I go further, I should explain that I am not a Network specialist. …

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Apr 26

Recreate Bad RAC Node

Just recently, I was trying to apply the latest and greatest Patch Set Update (PSU) to a 2-node Oracle RAC system. Everything went smoothly on the first node. I did have problems when trying to apply the PSU to the second node. The problem wasn’t with OPatch or the PSU, but rather, I could not …

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Apr 12

Oracle RAC N+1 Redundancy

I find that when people are designing Oracle RAC architecture, they often do not think of N+1 redundancy in their implementation plans. There are two reasons to implement Oracle RAC, availability and scalability. For the purposes of this discussion, I am focusing only on the availability side. If your RAC deployments are for scalability reasons …

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Jan 26

Identifying ASH Sequence Contention in RAC

In Chapter 3 of Oracle RAC Performance Tuning, I showed how improper CACHE values for sequences can cause poor performance in Oracle RAC. I also showed how to spot sequence contention when looking at a session’s wait events. Today, I was working with a developer who was creating a new sequence. The developer had a …

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Dec 22

A Trip Through the GIMR

Oracle Grid Infrastructure includes the Cluster Health Monitor (CHM) which regularly captures OS-related performance information. In early versions, CHM use a Berkeley DB for its data store. In Grid Infrastructure, it is now required to use an Oracle database for the data store. This Oracle database is called the Grid Infrastructure Management Repository (GIMR). …

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Nov 30

cd: -M: invalid option

I’m trying to clean up trace files on one of my RAC testbeds. Oracle Corp was gracious enough to name the database “-MGMTDB” for me to give me a nice challenge (dripping with sarcasm). Here I am in my DIAGNOTIC_DEST and we can see two databases. [oracle@host01 trace]$ cd /u01/app/oracle/diag/rdbms [oracle@host01 rdbms]$ ls -l total …

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Nov 11

Addnode resolv.conf Failures

Today I was trying to add a new node to an existing Oracle RAC cluster. Grid Infrastructure is version running on Oracle Linux 5.11. I ran through the usual Cluster Verification Utility (CVU) checks and all checks passed. To add the node, I issued the following command from the $GRID_HOME/addnode directory. ./ -silent “CLUSTER_NEW_NODES={newnode}” “CLUSTER_NEW_VIRTUAL_HOSTNAMES={newnode-vip}” …

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Nov 05

Adaptive Dynamic Stats Kills Performance in RAC

After a recent upgrade to, I’ve been working on a number of performance issues. Many such issues are related to poor SQL and a number of issues I’ve resolved I’ve proven were issues in the old release. This just means it’s always been an issue. But people are taking the opportunity of the …

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