May 22
I recently ran into a case where selecting the next value from a sequence was causing contention issues in Oracle RAC. See this screen shot from Lighty (click on the image to see a larger picture) The wait events will look the same if viewed in Enterprise Manager’s performance screens, which does require one to …
Jun 29
I am in the process of replacing production hardware for an Oracle RAC database. To do this with zero downtime, I am adding the new nodes and then extending the RAC database to run on both old and new nodes. Then I will remove the old nodes once they no longer have any database connections. …
May 18
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 12.2.0.1, I need to add more …
Feb 23
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 …
Jun 07
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. …
Apr 26
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 …
Apr 12
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 …
Jan 26
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 …
Dec 22
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 12.1.0.2, it is now required to use an Oracle database for the data store. This Oracle database is called the Grid Infrastructure Management Repository (GIMR). …
Nov 30
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 …
