Unable to find the sources of your current Linux kernel

When you are installing Oracle Linux (or other distributions) within a Oracle VirtualBox virtualization environment you do want to install the Guest Additions most likely. Depending on what you have included in your installation you might be missing some packages which result in failure of the installation of the Guest Additions.

Last “version” of this issue I encountered was represented by this error message:

The headers for the current running kernel were not found. 
If the following module compilation fails then this could be the reason.


Building the main Guest Additions module ...fail!
(Look at /var/log/vboxadd-install.log to find out what went wrong)

When you take a look in the mentioned log located in /var/log/vboxadd-install.log I encountered the following line:

Failed to install using DKMS, attempting to install without
/tmp/vbox.0/Makefile.include.header:94: *** Error: unable to find the sources of your current Linux kernel. Specify KERN_DIR= and run Make again.  Stop.

This indicates that you do not have all the packages you need to rebuild some of the kernel parts. To resolve this you have to install the following GCC, kernel-dev and kernel-headers. You can do so by executing the following yum command:

yum install gcc kernel-devel kernel-headers

That is under the impression that you have already configured your yum repository to your enterprise yum repository or to the public yum server available online at Oracle. If you have not configured yum you can read in this blogpost how you should configure your yum settings.

Secondly you have to make sure you have a variable names KERN_DIR pointing to your sources kernel. In my case this is /usr/src/kernerls/2.6.32-131.0.15.el6.i686

Oracle Enterprises Manager Topology Adobe SVG

Oracle Enterprise manager provides you the option to see the topolgy of a service. When you open this page you can however encounter a page which states the following;

“You are seeing this page because you do not have the Adobe SVG Plugin installed. To view the visual topology, please download the Adobe SVG Plugin 3.0.x”

This is the case when you open for example the topology page from a service as shown in the screenshot below:

Strange thing is that Adobe has stated they will discontinue SVG viewer as from January 2009. You can however still download the installer from the adobe site. You can also go to the plugin website from Microsoft to download a SVG plugin.

SVG stands for Scalable Vector Graphics and is a text-based graphics language that describes images with vector shapes, text, and embedded raster graphics.

SVG files are compact and provide high-quality graphics on the Web, in print, and on resource-limited handeld devices. In addition, SVG supports scripting and animation, so is ideal for interactive, data-driven, personalized graphics.

SVG is a royalty-free vendor-neutral open standard developed under the W3C (World Wide Web Consortium) Process.

After installing this plugin you will be able to view the topology pages in Oracle Enterprise Manager without any issue.

Oracle Enterprise Manager edit target properties

Oracle Enterprise Manager is designed to help you monitor and maintain servers and systems in large scale enterprise environments and not so much to be used within a small company with only a couple of database servers. You can use it however if you look at the way the products is build you see that the intention is to deploy and use in large scale.  When you are talking about maintaining large number of systems for multiple departments or even for multiple customers if you host and maintain systems for a large number of customers. 

When you use it in such an environment you would like to store more information about the system than you get from a discovery. If you go to “target setup” and select Properties you can add more information to the target.  

For example who to contact, which department and very important, what kind of server / service is this? Development, Production, Test,...

Oracle Enterprise Manager change dashboard

Oracle Enterprise Manager is a great solution to get a 360 view on your complete IT landscape and to enable the IT staff from you company to act fast and become more efficient. Even though you have a enormous set of options within Oracle Enterprise Manager and with the move to cloud management they make a very good case for the tool there are still some points. First and foremost is that the price is on the high side. If you already have invested for years in optimizing your IT the costs for the final optimization in the form of Oracle Enterprise Manager can come as a shock as the benefits will not be that extreme. Second thing is that you can see possibly to much.

For a tool that provide you a complete view on your hardware, operating systems, databases and applications from one single tool that might sound a little strange however it is true. Without a good and well thought setup plan your administrators will be to overwhelmed to be efficient. It is of vital importance that you think about who can see what and who can do what. In essence everyone within your own organization should be able to see everything however their main dashboards should be tuned to show them the most important and critical information when they open Oracle Enterprise Manager. For example a UNIX administrator will not have to see all the database information on his first screen, what this person needs is the information of all the servers running. By default you get a somewhat overwhelming screen as shown below;

You can change this by navigating to “setup” > “My Preferences” > “Select my Home”. By default you have 7 options in this screen where you can pick the most appropriate for your daily job. You have the following options:


Summary: Summary page provides a complete and consolidated view of targets monitored by Enterprise Manager.

Databases: Monitor any database instance or RAC database right on the homepage. Check the load, memory consumption and any issues related to the target.

Incidents: Incident console helps users track, diagnose and resolve issues identified across targets by Enterprise Manager.

SOA: An enterprise level view for all the SOA targets with the Alerts, Policy Violations, and critical metrics. It provides details of SOA Composites, BPEL 10g Process, OSB Services and Web Services.

Middleware: Monitor all middleware targets in your environment from this page.

Composite Application: An enterprise level view of Composite Applications. It provides list of all Composite Applications created with their member details along with status information.

Service Request: The Service Request page provides access to the Service Request creation and management features in My Oracle Support, Oracle's customer support portal.

Selecting one of those will change the default first page to a more appropriate page for your day to day job.

Multiple online identities

Chris Pool is the founder of 4chan and Canvas and during his talk at the web 2.0 summit sponsored by O’Reilly he gives the below talk on online identity.



During his talk he is stating some very good points to which I can relate. One of his main issues the current way online identities are managed today by for example facebook and google is that you can only have one single identity which needs to be linked to the person who you are in real life. Having a connection between your online identity and your offline identity is not a bad thing at its self however, it is within the human nature to have multiple identities. The average human will have multiple identities and will be able to tell them apart from each other without having a mental issue. As an example the identity which identifies you as a person at the work will be most likely something else as how people identify you at your sports club. Your family will know you as yet another person.

When sharing with your facebook identity all people will be able to read what you share, with this facebook is a real one identity network. Google has launched google+ where you can use circles where you group people. You can share with everyone or with only the people in a certain circle. This is already a more segregated way of sharing and provides you to have multiple channels of expression under one single identity.

What Chris is promoting in his talk at the web 2.0 summit is that you should also have the option to post under an alias (handle). Just to make sure that you can explore all kinds of different things you do not need to inform other people about (or explicitly do not want other people to know). For example what do your coworkers need to know about your interest in ancient fire making techniques, maybe this is something private you only want to discuss online using your handle makefire1600 while you do not want your makefire friends to mingle with the people from you daily job.

There are all kinds of things to say for having the option to be able to multiple id’s online and it would be great if you can connect them all to one username/password protected main identity without showing who you really are. If companies like Google and facebook will ever go to this kind of account setup is a very big question and I do not think they will start supporting it however, it is a interesting question and theory to play with and I do think Chris has a point.

Excel hell

At all the companies I have worked for, as own staff or as a consultant for a certain period of time I have encountered the lover for Microsoft excel or spreadsheet applications of another vendor. Reason for this is that people can quickly create and work with spreadsheets, use them to build analysis, create calculations and more. The ease of building it is great, almost all employees do have a copy of Excel on their laptop and most people do understand it. The phrase “excel management” is not an unknown term to most companies as it looks like managers especially love excel to look at reporting. When companies or departments need some more than Excel they tend to look at solutions like Microsoft Access which is more a database like application and is tending to some more “complex” needs a department might have.

Issue with especially excel and excel files is that as soon as you put it out in the wild, you mail it to other people to use it, you do no longer have control over it. For example if you create a calculation model for something into excel and send it to other people in the company you do not have the option to track who is using it and if you discover something that you need to change there is no way of knowing all people will use the latest version. A similar issue is that when you like to keep track of the status of things in a excel sheet, for example the progress of work, you have no way of knowing and assuring that all people use the same version and that everything is captured.

In many cases the file is placed on a centralized storage location, for example a department shared network location, issue is that people tend to download it and place it on their own laptop. For example the project progress, people working remote will update the sheet on their local drive and when they have a network connection again try to upload / override the version on the network drive. I imagine everyone working on such projects will have an example of versions that where overwriting someone else his work.

To cope with this issue it might be more easy to have a centralized web application that holds all the features that excel is offering you and enable you to make more use of collaboration functions. Some options are available currently. You can have a look at the Microsoft 365 online office applications, Google is providing Google Docs which holds a spreadsheet application or you can have a look at Oracle APEX (Oracle Application Express). Oracle APEX is not comparable with the Microsoft 365 or Google doc solutions which are more online spreadsheet solutions, APEX is more a quick solution to build applications with a spreadsheet background.

APEX provides you the options to quickly build a web application and even convert existing excel spreadsheets into such an application. All user interface parts are provided out of the box as well as user management and such things. With APEX you can have an application up and running in no time by only using your browser and without any programming needed. In my opinion it is not a hundred percent solution however for quickly building spreadsheet avoiding solutions or small applications for a departmental level it is a great application. In the video below you can see what Oracle has to say about their own product. Big advantages are that that you can install it even on your own laptop to play with it and experiment with it, it is easy to use and build upon and the price…. You can use it for free under certain rules.