linux

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

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.

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 […]

Dear Linux Hackers, Have we not finished changing the 'best' way to have persistent naming and security attributes for disk devices? Seriously, just when we thought it was great to put the "uid", "gid" and "mode" specifications for disk devices into /etc/multipath.conf, then it gets once again deprecated in favour of udev. This push and [...]

I’ve just tried the alpha of Fedora 17 to see if the GNOME 3 software rendering works and it did. You may recall, since updating my graphics card I’ve been forced to use the fallback mode on Fedora 16. I’m quite keen to move back to proper GNOME 3, which looks like it will be possible when F17 is released.

On a VM it seems a little on the slow side, so I hope this isn’t an indication that it will be annoying on my desktop. I guess time will tell. Fingers crossed though.

Cheers

Tim…

Lenz Grimmer blogged today about the release of the “oracle-rdbms-server-11gR2-preinstall” package, the Oracle Linux 6 version of the “oracle-validated” package we know and love.

I did a run through of an installation using it and it does exactly what it says it will. I’ve modified my 11gR2 installation on OL6 article accordingly.

Cheers

Tim…

I had the great pleasure to spend the better part of last week at the Norwegian Oracle User Group’s spring conference. Martin Nash and I helped promote the Real Application Cluster platform on the attendees’ laptop in a program called RAC Attack.  RAC Attack has its home on the wikibooks website http://racattack.org where the whole program is documented and available for self-study. The purpose of the hands-on labs which Jeremy Schneider started a few years ago is to allow users to get practical experience installing Oracle Linux, Grid Infrastructure and the RDBMS binaries before creating a two node database. Following the database creation a practical session ensues which explains certain HA concepts with RAC such as session failover. We are planning on greatly enhancing the lab session as we go along. If you have any suggestions about what you would like to see covered by us then please let us know!

I’ve just put another batch of Linux articles live.

Quick post to bring the Virtual Box PDF to the attendees. Follow this link to get the instructions

RAC Attack Using VirtualBox

UPDATE

This post was the best way to get the PDF instructions to participants of the OUGN 2012 RAC Attack seminar without too much effort on our side. If you have since then used your favourite search engine and ended up here in the hope that there is an interesting story please navigate here instead:

http://martincarstenbach.wordpress.com/2012/03/26/ougn-spring-meeting-2012/

Thanks for passing by!

This is a very quick post to remind users of the importance of large pages. Before 11.2.0.2 it was a little more elaborate process to determine the number of large pages to be set aside for Oracle, but now it’s so simple there isn’t any more excuse not to use large pages. If you have > 16G SGA and lots of processes, check the impact of large pages in /proc/meminfo before and after. By implementing large pages at a former company I reduced the page tables overhead from 20G (60G sga, processes set to 1000, most often around 800 sessions connected) to a fraction of that number.

Here is why you can’t hide anymore: