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April 2012

VirtualBox 4.1.14 Released…

VirtualBox 4.1.14 is ready for download. It’s a maintenance release, with fixes listed in the changelog.

Happy upgrading.



Avengers Assemble…

If you have ever enjoyed a superhero film in your life you simply must go to see Avengers Assemble. It is totally fantastic. It has great action scenes, some really neat characters and is really funny at times too. I’ve not enjoyed an action film this much since I saw the first Iron Man Film. Awesome!!!

Iron Man/Tony Stark : I want to be him. He is too cool for school. He is Kool and the Gang.

The Hulk : All The Hulk films have been a bit of a let down because the only thing I really like is the green monster running around destroying things. The great thing about this film is it doesn’t have to fill two hours with the story of Bruce Banner, so you just get to see the bit you really want to see. The Hulk is fantastic in this film and adds greatly to the comedy elements. He literally had the whole audience laughing hard on several occasions.

Ardent Performance Computing

Jeremy Schneider

IOT Secondary Indexes – The Logical ROWID Guess Component Part I (Lucky)

As discussed previously, an index entry within a Secondary Index on an Index Organized Table (IOT) basically consists of the indexed column(s) and the Logical Rowid, the PK column(s) and a “guess” to the physical block in the IOT containing the corresponding row. Let’s discuss this “guess” component in a bit more detail. When the Secondary [...]

Xeon E5-2600 OS CPU To Core / SMT Thread Mapping On Linux. It Matters.

Ages ago I blogged about the Intel topology tool and mapping Xeon 5500 (Nehalem EP) processor threads to OS CPUs on Linux. I don’t recall if I ever blogged the same about Xeon 5600 (Westmere EP) but I’ll cover that processor and Xeon E5-2600 in this short post.  Fist, Xeon 5600.

The following two screen shots are socket 0 and socket 1 from a Xeon 5600 server. Socket 0 first:

Now, socket 1:

Collaborate 2012 Sessions and Select Article

Thank you all who came to my sessions at #IOUG Collaborate 2012 #C12LV on April 22-24 in Las Vegas. I had four full sessions, two panels and one bootcamp. Quite a busy schedule, as you can see. I also worked on some urgent performance issues at work during the week.

You can download the the slides and scripts here. They are available from the IOUG site but I thought I would put them for download here as well.

Getting to know Oracle wait events in Linux.

May 4th: some updates after discussion with Jeff Holt, Cary Millsap and Ron Christo of Method-R.

There’s all the documentation, and there all the terrific blogs about performance and Oracle wait events. But if you more or less start with this stuff, or encounter a wait event that is not (extensive enough) documented, or an event turns up and gives a response time you don’t expect, you need to understand what that wait event means. If you don’t know, it’s easy to get stuck at this point.

If you are familiar with waits, and just want to dig further, progress to “Get to know wait events”, if you want to get up speed with waits, read on.

What is a wait event?

This is the definition of the performance tuning guide in the Oracle documentation:

Linux Firewall and SELinux (RHCSA)…

I’ve put the last two articles in the RHSCA certification series live.

Limit nmon to certain disks

I am often working on systems with large number of LUNs, going into the hundreds. Trying to keep track is difficult at best. Sometimes though you might want to limit yourself to a specific number of disks-I knew about the dskfilt option in collectl but only today learned about a similar feature in nmon. The following is a very greatly simplified example of course, but it gives you the idea.

Assume you are interested in 4 disks-sd{a,b,c,d}. Let’s further assume that your disks are used for 2 ASM disk groups, DATA and RECO. You could create a file “disks.dat” with the following contents:

DATA sda sdb
RECO sdc sdd

Then pass that file to nmon with the -g flag. When you type “g” now, you are shown IO stats for those disks.

Understanding Linux Load Average – Part 1

A frequently asked question in my classroom is “What is the meaning of load average and when is it too high?”. This may sound like an easy question, and I really thought it was, but recently I discovered that things aren’t always that easy as they seem. In this first of a three-part post I […]