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July 2012

Instrumentation

At first this post might seem off-topic, but it's a post that I've been planning to write for a long time because, even if it might seem a bit of fluffy fun, it reinforces one of the most important tools at your disposal.

Instrumentation in your code is pure gold when it comes to analysing performance.

Without instrumentation you're flying blind and, although most people in the Oracle community are familiar with the importance of instrumentation via the Wait Interface, 10046 trace files, ASH data, the PL/SQL Profiler and so on, I wanted to discuss a very early example of my own experience with instrumentation to illustrate that this stuff has been around for a long time!

I learnt this lesson when I was around 17 years old (which means, erm 29 years ago or so). When I first started developing commercial games for the ZX Spectrum, some of the most important questions I had to ask where things like ...

Swingbench Download should be ok

Following up from one of the questions raised during last week's OEM webinar I did for Red Gate Software, it appears that others have reported the issues with Dominic Giles website where you can download his Swingbench tool. Dominic has now taken action to resolve the issues and you should be good to access the site again.

I was surprised to say the least because it wasn't so long ago that I was downloading Swingbench for a new VM build, but that was probably a few months ago now that I think of it.

Thanks to those who raised the question during the webinar and particularly Brian Pardy for sending me a message with an example screenshot.

OTN Tour of Latin America 2012: Quito, Ecuador…

Getting to Ecuador from Colombia was really quick and easy. I think the flight time from Cali was about 45 minutes. :) We arrived late in the day, so it was bed and straight to the conference.

We had a little car trouble on the way to the venue, so we were a little late. Fortunately my laptop was ready to plug in and go, so that’s what I did. I think the translators got an easier time during this conference, because I got the speed of my presentations about right. Both talks went well and I got to speak to a lot of people between sessions. I also got to do an interview for the user group and a local computer magazine. I was famous for 15 seconds in Quito. :)

OEM 12c Agent Consuming High Levels of CPU

Just a quick note that some Oracle users have been seeing problems with the OEM 12c agent consuming high levels of CPU on hosts where it is running. This was brought to my attention by Andrew Bulloch of Oracle via this blog post. Definitely one worth following for OEM users!

I'll need to check with my client tomorrow whether we've been experiencing this but their deployment is still at a relatively early stage ...

OTN Tour of Latin America 2012: Cali, Colombia…

Let me start by apologising for spelling Colombia incorrectly on previous posts. I think I’ve corrected all the mistakes (I hope). Also, the name of the tour doesn’t really reflect the actual locations, since it contains two South American, one Caribbean and three Central American countries. I’ve heard multiple names for the tour, none of which are quite correct for all the countries involved, so I’m going to stick with this name for the sake of consistency. Once again, sorry if any people don’t like the tour name…

Update: I switched to “Latin America”, since this fits more of the countries (5/6). :)

Broken Technology – Watching Smurfs Play Tennis

This post is just a bit of fun. I was just doing some email and I decided to see how the tennis (Wimbledon) was going. I fired up the BBC web site and clicked on the live match – and I’m watching Smurfs play tennis! (NB I added the Federer/Murray picture after I originally put this post up)

 

ASM normal redundancy with high protection template

One of the ways you can control how many mirror copies ASM keeps on disk is via diskgroup templates.

This presents an interesting question -- can you turn your normal redundancy disk group into a high redundancy by using a diskgroup template with high protection attribute thus telling ASM to use triple mirroring for related files?

I'll start by creating a diskgroup:



SQL> create diskgroup data normal redundancy
2 disk '/dev/sdb1', '/dev/sdc1', '/dev/sdd1';

Diskgroup created.

I'm not explicitly specifying any failgroups, each disk will end up in it's own FG and triple-mirroring will spread extents across all three disks. Let's add a high protection template:

SQL> alter diskgroup data add template mirror_high attributes (high coarse);

Fault Injection Testing. Spurious Space Depletion? Sure, Why Not?

When file systems run out of space bad things happen. We like to investigate what those “bad things” are but to do so we have to create artificially small installation directories and run CPU-intensive programs to deplete the remaining space. There is a better way on modern Linux systems.

If you should find yourself performing Linux platform fault-injection testing you might care to add spurious space free failures. The fallocate() routine immediately allocates the specified amount of file system space to an open file.  It might be interesting to inject random space depletion in such areas as Oracle Clusterware (Grid Infrastructure) installation directories or application logging directories. Could a node ejection occur if all file system space immediately disappeared? What would that look like on the survivors? What happens if large swaths of space disappear and reappear? Be creative with your destructive tendencies and find out!

 

Histograms – What is Wrong with this Quote?

July 4, 2012 It has been several months since I posted my review of the first half of the “Oracle Database 11gR2 Performance Tuning Cookbook” book.  I had planned to post the review for the second half of the book a couple of weeks later, however four months have passed by since that time, and the second [...]