Solved wireless issue on Compaq 420 laptop

My laptop ( Compaq 420 ) is armed with CentOS 6. Freshly installed.
There was some issue with the wifi driver, because of which I remained connected to a wired network.
I sat and spent some time in troubleshooting it and landed up with solutions posted on CentOS forum.
Few details regarding the Operating System :
[root@ashutosh ~]# uname -arm
Linux ashutosh 2.6.32-279.22.1.el6.x86_64 #1 SMP Wed Feb 6 03:10:46 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux

[root@ashutosh ~]# lspci | grep controller
00:02.0 VGA compatible controller: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller (rev 07)
00:02.1 Display controller: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller (rev 07)
00:1a.0 USB controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #4 (rev 03)
00:1a.1 USB controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #5 (rev 03)
00:1a.2 USB controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #6 (rev 03)
00:1a.7 USB controller: Intel Corporation 82801I (ICH9 Family) USB2 EHCI Controller #2 (rev 03)
00:1d.0 USB controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #1 (rev 03)
00:1d.1 USB controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #2 (rev 03)
00:1d.2 USB controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #3 (rev 03)
00:1d.7 USB controller: Intel Corporation 82801I (ICH9 Family) USB2 EHCI Controller #1 (rev 03)
02:00.0 Network controller: Realtek Semiconductor Co., Ltd. RTL8191SEvA Wireless LAN Controller (rev 10)
85:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8101E/RTL8102E PCI Express Fast Ethernet controller (rev 02)

From the above output it’s clear that the laptop has a Realtek RTL8191SEvA Wireless device.
Luckily it’s supported by the kmod-8192se package from ELRepo. Please follow the instructions to setup ELRepo repository and install the package by :
yum install kmod-r8192se
and reboot.
Wireless works out of the box.


Exploring SuSE Studio

I started exploring with SuSE Studio at work when I found issues working with various hardware ; installing and re-installing virtual machines on them for testing software patches which were released at very short interval of time. I had issues with logging in to SuSE Studio website earlier which is now resolved as per this blog post. I am now creating appliances for various test suites and in a process to upload them for users. I will better write a page on my experiences once am done with building appliances.

DevOps Days India 2011

DevOps Days is an open event which is typically considered as an interaction between what is traditionally considered as Development activity and an Operations activity. I added up to Operations activity for this two day event held at ThoughtWorks, Bangalore on 27-28 August 2011. There were talks, interactive sessions and OpenSpace sessions altogether.
The first day began with a welcome talk by Ajey Gore, followed by talk by Nick Hines on Continuous Delivery. Nick was focusing on things like – basic fundamentals, automation, branching,right sizing, continuous improvements; Development practices like automation testing, code on mainline, branching by abstractions, non-functional automation testing, Build – development pattern : build-pipeline, canary releasing. Tooling: Chef, Puppet, CFEngine, Infrastructure as a Code.
The other interesting talk given by speakers from Infosys – “Why is it difficult to do Test Driven Development and Continuous Integration in large companies ?” was an eye opener. Mainly because of maintenance, reliability and performance, feature release, investments in process automation, culture change, dependencies. Mirror environments , need for constant change, split of activities, maturity levels. These were those immense factors which made them think twice before adopting it and deviating from patterns.
Test Load Balancer [ TLB ] was the talk which I liked the most ; it splits tests into multiple mutually exclusive and collectively exhaustive partitions and allows it to run in parallel to reduce build time. There were speakers from SlideShare who presented how they were able to build a system that deploys 5 times a day in a production environment. I attended OpenSpace sessions by techs from MakeMyTrip on Monitoring Systems using Nagios, Puppet, Ganglia. They also mentioned about identifying metric for monitoring, they have their own inventory system to deal with each clusters.
Second day witnessed a talk by Garrett Honeycutt from Puppet Labs which was so worth learning that I did mention about it’s usage in my organisation. We can have hosts on demand, reduce entropy, disaster recovery, infrastructure as a code, usage of dashboard. Automate most of the activities on nodes. Garrett’s talk’s slide is available here
I am not a Ruby guy but could definitely understand it’s power – Ajey & Nikhil spoke on Deployment Pattern in Ruby on Rails world. Ajey’s openspace session was the last thing I attended, went on for more that 45mins and got to know about reducing build times from few days to few hours using automated deployment. Things that they concentrate while setting up an environment – define a standard hardware, choose OS, configurations and provisioning them.
Had a rich experience at the event followed by meeting some old faces too. It’s four years now since I am with Systems and working in Operations, but yes is DevOps solving issues like – (1) Afraid of changing once application is delivered. (2) Risky deployments (3) It works on my machine.

The DevOps movement is still in its infancy, but it’s gathering pace – there are conferences, mailing lists, irc channels, blogs and people to get to know. I’m convinced this isn’t just a fad, and we’re on the brink of a revolution in the software industry – a paradigm shift in which developers and sysadmins start to work together, to train each other, and ultimately to blur the boundary – welcome to the world of the DevOps.

Firefox: “Save and Quit” option disappeared ?

I was finding it difficult to save my currently opened tabs whenever I quit Firefox browser ; later I learnt that up from Firefox 4, one change that has been brought is to by default stop Firefox displaying warning messages. It can be changed from the preferences.
Here is how I learnt a way to get back “Save and Quit” option in Firefox 6.0 which has disappeared somehow :
1. Type about:config into the location bar and press Enter.
2. Accept any warning messages that pops up. You will be taken to list of preferences.
3. Locate the preference browser.tabs.warnOnClose, if its value is set to false, double-click on it to change it’s state to true
4.Repeat this for 3 other preferences browser.warnOnQuit, browser.warnOnRestart and browser.showQuitWarning

Happy browsing !

Yahoo! Open Hack India – 2011

It was the fourth hack event conducted by Yahoo! in India and my first hack event in Bangalore. I do not use most of the Yahoo! technologies while at work, but yes did some stuffs using Y! Pipes, Yahoo! Travels. What called me to this event was the enthusiastic crowd and the kind of hack ( software / hardware ) which was going to happen during this two day event. JavaScript guru Douglas Crockford, has come down for the event.
The event kicked off with some technical talks by Y! folks. YQL, Geo-hacking and OAuth sessions were worth attending. Most of the applications developed during the hack used one of these. YQL turns data on the web into databases. Geo-hacking involved things like – finding a current location, turning a location into a place, finding geographical hierarchy, geo-tagging information, displaying geo-information. Learnt about BOSS [ Build your Own Search Service ], since the back-end is proprietary and owned by Microsoft, one has to pay 80cents per 1000 query. DuckDuckGo uses BOSS for it’s search engine. Did interact with Y! folks discussing stuffs related to systems rather than web scale applications. Got to know about happenings at Y! Labs.
Hack challenges : Location based, Mobile based, Entertainment based. Hackers were asked to come up with applications using Y! open technology mostly available at Y! Developer Network and their latest open platforms. It was time to come up with some ideas and put them in some structure. Teams were formed and few did an individual hack as well. An applications named ‘FakeMyTrip’ wherein a user can put his photo to any fake location (s)he wish to visit, was applauded a lot. There were hardware hacks too – showing mind’s concentration while moving a remote control toy car, LED indicators which shows amount of CPU, memory consumed when a site is loaded, LED indicator glows red when a child tries to access unauthorised websites. 50 finalist were selected and they were given 90 secs to demo it. Grand prize was a trip to New York to participate in Y! Hack All Stars Event, where winner will compete with winners of other open hacks from around the world.
The grand prize winners were actually two – [1] Spotlight – Illuminate your part of the World ( Find out best place to hangout ) [2] D.A.M.N. – Single Serving Friend ( connects people on demand to share meter fare in auto-rickshaw / taxis )
It was a privilege meeting techies from Yahoo!. The event was a place of good learning and experience.

How far will you get with “rm -rf /” on Linux ?

Have you ever left your Terminal logged in,  only to find a so called friend/ colleague came up and typed ” rm -rf / ” ?

I actually did so on a virtual machine (VM). It’s a CentOS VM which was used for some applications test. I created a backup of this VM and thought of shooting a video as I proceed to run ” rm -rfv / ” on it.

You can watch my video recordings here.

I also did so to learn what all directories do not get deleted with this command. And also, after the command has executed  will “rm” have removed itself  ? It seems that OS protects certain directories like /sys, /proc, /dev. At the end of the video you can see that “ls” command is not found and so is “/bin/rm”. Needless to say /bin, together with /bin/echo has been deleted. So, issuing ” echo * ”  just displayed * at the promt. I rebooted the VM and ended up with a black screen. OS is gone !! After the command finishes, disk is wiped off, including the OS. The Kernel and current processes will continue to run from memory, but many processes will die because they fail to access some file. OS will obviously fail to boot next time.

Still unanswered – Files that is currently open ( i.e rm ) even if deleted, won’t disappear from disk until closed.  I am not sure, if it is safe to assume,  the Kernel could very well load the removed file into memory and remove it from disk immediately ; and keep this memory copy running until the command is open  (  i.e rm is running )

Mistakenly, do not run this command on host system’s terminal. I did so on a VM, else you will land up putting your head on hand, hand between knees ! as one who’s world has just come to an end.

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