Monthly Archives: November 2011

Getting started with Xen virtualisation on Ubuntu 11.10

After a long time and lots of problems I decided to abandon openSuSE 11.4 and its xen implementation in favour of the PVOPS kernel and a different distribution.

It’s been difficult to choose the correct one for me, for now I’m working with Ubuntu 11.10. One reason is that it’s said to be user friendly, and highly customisable. It comes with all the right ingredients for running different hypervisors, including my favourite: xen.

Important update! See “Security” below.

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Installing OEM 12c agents in RPM format

One of the questions I have always asked myself revolved around: “why doesn’t Oracle package certain software as an RPM on Linux?” Well this question has recently been answered in the form of the Oracle 12c agent. It IS possible to use an RPM based installation, although it doesn’t make 100 use of RPM. I have written this post to give you an idea what happens.

The procedure is described in the OEM 12 Cloud Control Advanced Installation and Configuration Guide, chapter 6. The process is very similar to the non-RPM based agent deployment. Let’s have a loot at it in detail.

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Simplified GNS setup for RAC and newer

One of the main problems I have seen with GNS (Grid Naming Service) installations was that you couldn’t really see if your DNS and DHCP configuration was correct until it’s been too late. This has been addressed, but it’s little known. There are a number of checks you can run before starting Oracle Universal Installer, and this post is about them.

What is the Grid Naming System?

I was initially drawn towards the GNS when it was initially released with It is aimed at environments where the Oracle DBAs take on (yet another) piece of work, namely the DNS administration. By virtue of “subdomain delegation”, the master DNS server responsible for “” hands off requests for a subdomain to this – – to an Oracle managed process. This was quite poorly documented initially, prompting me to figure it out myself in an earlier post:

The problem with GNS in was that you couldn’t really test if the DNS setup was sufficient for Oracle Installer to work, and I had a few attempts at the installation (the discussion here takes into account that I might not have been able to perform sufficient checking!)

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Installing FreeNX on OpenSuSE 11.4

After reading an article in one of my favourite computer magazines about FreeNX and NoMashine’s NX I was very interested to get this to work. Also, google are using NX for some developers-and if a technology is good enough for google than it can only be good enough for me as well.

Unfortunately there wasn’t an awful lot of documentation around for openSuSE 11.4 but by making best use of search engines I finally got it to work. Again, this is looking rather trivial in the post but was a lot of work finding out! Now here’s what I did.

Installing FreeNX

I found the RPMs for FreeNX in the standard SuSE repositories, but there are probably newer builds to be found here:

It seems to be sufficient to install these packages on the server:

#  rpm -qa|grep -i nx

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An interesting problem with ext4 on Oracle Linux 5.5

I have run into an interesting problem with my Red Hat 5.5 installation. Naively I assumed that ext4 has been around for a long time it would be stable. For a test I performed for a friend, I created my database files on a file system formatted with ext4 and mounted it the same way I would have mounted an ext3 file system:

$ mount | grep ext4
/dev/mapper/mpath43p1 on /u02/oradata type ext4 (rw)

Now when I tried to create a data file within a tablespace of a certain size, I got block corruption which I found very interesting. My first thought was: you must have a corruption of the file system. So I shut down all processes accessing /u02/oradata and gave the file system a thorough checking. Continue reading