rac

rshamsud's picture

gc cr disk read

You might encounter RAC wait event ‘gc cr disk read’ in 11.2 while tuning your applications in RAC environment. Let’s probe this wait event to understand why a session would wait for this wait event.

Understanding the wait event

Let’s say that a foreground process running in node 1, is trying to access a block using a SELECT statement and that block is not in the local cache. To maintain the read consistency, foreground process will require the block consistent with the query SCN. Then the sequence of operation is(simplified):

rshamsud's picture

RMOUG 2012 – Hello Denver!

On February 14-16, I’ll be at the Colorado Convention Center in Denver, Colorado for RMOUG’s Training Days Conference. This is the largest regional Oracle User Conference in North America and attracts presenters from all around the country and the globe. I’ll be presenting:

Presentation Name: Troubleshooting RAC Background Process

Abstract: RAC background process performance is critical to keep the application performance. This session will demo techniques to review the performance of RAC background processes such as LMS, LMD, LMON, etc. using various statistics and UNIX tools. The presentation will also discuss why certain background processes must run in higher priority to maintain the application performance in RAC.

Presentation Name: A Kind and Gentle Introduction to RAC

oraclebase's picture

DNS Config for RAC SCAN… Again…

Some time ago I wrote an article about configuring DNS for the SCAN address in Oracle 11gR2 RAC.

Over the last couple of days one of the Oakies has given me some feedback on the article based on his experiences with Oracle Linux 5.

For my virtual RAC installations I typically do the DNS configuration on the host machine, which is running Fedora. It seems Oracle Linux 5 is a little different. Just to make sure I ran through the setup on Oracle Linux 5 and 6 to see what the score was.

rshamsud's picture

Troubleshooting ‘DFS lock handle’ waits

Waits for ‘DFS lock handle’ can cause massive performance issues in a busy RAC cluster. In this blog entry, we will explore the DFS lock handle wait event, and understand how to troubleshoot the root cause of these waits. I am also going to use locks and resources interchangeably in this blog, but internally, they are two different types of structures.

A little background

DFS (stands for Distributed File System) is an ancient name, associated with cluster file system operations, in a Lock manager supplied by vendors in Oracle Parallel Server Environment (prior name for RAC). But, this wait event has morphed and is now associated with waits irrelevant to database files also. Hence, it is imperative to understand the underlying details to debug the ‘DFS lock handle’ waits.

How does it work?

martin.bach's picture

The tale of restoring the OCR and voting files on Linux for RAC 11.2.0.2

As part of a server move from one data centre to another I enjoyed working in the depths of Clusterware. This one has been a rather simple case though: the public IP addresses were the only part of the package to change: simple. One caveat though was the recreation of the OCR disk group I am using for the OCR and 3 copies of the voting file. I decided to reply on the backups I took before the server move.

Once the kit has been rewired in the new data centre, it was time to get active. The /etc/multipath.conf file had to be touched to add the new LUNs for my +OCR disk group. I have described the processes in a number of articles, for example here:

http://martincarstenbach.wordpress.com/2011/01/14/adding-storage-dynamic...

A few facts before we start:

oraclebase's picture

Oracle Database on Oracle Linux 6.1…

I mentioned the day before Open World I put a Virtual RAC on Oracle Linux 6.1 article live. Although the procedure was complete, some of the screen shots were from an old article as I didn’t have time to redo them before my flight. :) I’ve just run through the procedure again and taken new screen shots. As a result, I’ve allowed the article to display on the front page of the website, which is why you will see it listed as a new article there.

This kinda rounds out the whole Oracle on 6.1 stuff as there has been a single instance installation guide out for ages and more recently the Cloud Control installation, which references it.

Remember, it’s still not certified yet, but it’s coming.

Cheers

Tim…




Jonathan Lewis's picture

Personal RAC

Thanks to Tim Hall, I can now show you a snapshot of OEM demonstrating my personal four-node RAC.

rshamsud's picture

Oracle Open World 2011 – My presentation on RAC topic

I will be talking about “Administering Parallel Execution in RAC” with demos on Sunday morning 9AM-10AM (session id 28060). This is part of IOUG RAC SIG presentation series. You would enjoy the content and demos I have prepared.

I know, it is too early, but hoping to see you there!
BTW, if you have attended my RAC Advanced Troubleshooting class series, please don’t hesitate to introduce yourself when we meet.

Session details:
Session ID: 28060
Session Title: IOUG: Administering Parallel Execution in Oracle RAC
Venue / Room: Moscone West- 2005
Date and Time: 10/2/11, 9:00 – 10:00

Update: I just completed this session in IOUG. Thank you for coming, if you were in the room.
You can download the pdf file from
PX execution in RAC

oraclebase's picture

Oracle 11gR2 RAC on Oracle Linux 6.1 using VirtualBox…

It’s all a bit last minute, but today I decided to do an Oracle 11gR2 (11.2.0.3) RAC installation on Oracle Linux 6.1 using VirtualBox. The 11.2.0.3 patch has fixed all of the installation issues related to RAC on OL6.1, so it was pretty smooth. The procedure can be seen here.

As noted in the article, the screen shots of the GI and DB installers are from an 11.2.0.1 article. I’ll update these screen shots when I get back from OpenWorld. Like I said, it was all a bit last minute. :) Normally I wouldn’t put an article like this live (and you can see it’s not on the homepage yet), but I get lots of questions about this subject, so I thought I would make it available to make my life easier.

Cheers

Tim..

PS. There is no suitable oracle-validated package available for this at the moment, so the prerequisites have to be done manually.




karlarao's picture

Oracle Database Appliance (ODA) Installation / Configuration

Earlier Oracle announced the Oracle Database Appliance which is a really cool RAC-in-a-box. And here at Enkitec office we are very lucky to get our hands dirty and play with this new beast </p />
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