Monthly Archives: July 2008

GLOSS Website and Geek Speak

Finally I am coming online after two weeks because of the poor wifi connectivity in my hostel. Anyways, in these two weeks, a lot has happened in GLOSS. The first is GLOSS has a new website which is linked to the SASTRA website! The site was developed by Abhishek and has many cool features like Forum, scrapbook, add friends, blogs and many more!!! One more sneak peek about the site is that we will have a blogger in the site who has won even an award from the President of India for blogging!!! The site will be inaugrated by the Dean, Mr. Vaidysubramaniam very soon. I will post the link here after it is inaugrated. The other one is Geek Speak.

Geek Speak is the show of GLOSS in my college radio 7Cube. It is hosted by Abhishek with Vikas and myself helping him with the show. The show will be on air every Tuesday from 8:30 PM to 10:30 PM. Today in the show we had loads of fun. Many dedications started pouring and we gave away some cool facts on technology. We announced a contest too and a first year won it. We asked two questions and she answered both of them. She wins an OpenSolaris tee shirt which will be presented to her soon in the next GLOSS session for first years. Her name is Akshaya and she is from my branch (ICT!!! :-)).

If you are in SASTRA open up VLC Media Player every Tuesday evening by 8:30 and Press Ctrl-N. Now enter the address and tune in to Geek Speak!


GLOSS Kicks Off For First Years!!!

Finally, yesterday GLOSS was inaugrated for first years. By morning 10, the event started in TIFAC CORE. Sanjeev designed a registration site for the first years and hosted it on the wifi. Some 108 students registered for it and there were a good mix from almost every branch. Abhishek, as usual, welcomed the freshers and gave a talk on OpenSource. The video which Guru Prasad made was also screened. I will post lots of pictures and the video also in my next blog. The session was a bit long (3 hours :-)) but many first years enjoyed it. There were a lot of funny happenings during the last session when they asked questions to Abhishek. That’s it for now. Bye guys!!!

First Virtual Conference in SASTRA!!!

Finally we did it!!! The first virtual world conference in SASTRA was successfully held this Wednesday! The conference started at TIFAC for boys and in Nirman for girls. We logged into the two avatars of Abhishek and we sat in the very first row of the Andromada Theatre at Sun Microsystems Islan (SL). They tried out some new technology this time it seems and it failed badly resulting in an audio failure. So we shifted to a text chat. After the initial chat by the big guns we started asking questions. The session was very interactive and we learned a lot of cool stuff. The session got over by 9:00 and we planned to roam around in the virtual world for some more time. When we were roaming around we saw Jonathan Schwartz!!! He just logged in and left somewhere so we couldn’t talk to him. Then we went to IBM office and some Desi club and a Hanuman temple too. Overall, it was a cool experience in the virtual world for all of us 🙂

Firefox record and GLOSS for First Years

Finally it’s official now, Firefox 3 has made the Guinness World record for the maximum number of downloads by any software in 24 hours. It was an amazing count of 8,002,530 downloads worldwide which made this record possible. That settles the first two words of the title. As for the remaining words, read further. GLOSS will be launched for first years on 12th of July 2008. Unlike our plan on 5th, we decided to give them some time for settling and also, our planned chief guests have some problems with coming here. So, on Saturday the 12th of July, we will start the GLOSS sessions for first years at JVC. Since Dwarakanath is the new campus ambassador and Abhishek has become the coordinator, he is no more in the organising team of GLOSS. So, we guys and Dwarakanath have to take care of organising the events. Already the preperations have started. I will keep you guys updated about the latest happenings. Bye for now!

GLOSS Inaugration and Cluster Computing

Yesterday evening, we inaugrated GLOSS for this semester with a session on Cluster Computing by Abhishek. In this blog, I m going to explain in detail the concepts of Cluster Computing to my Im am not going to write much about the session but I will definitely tell something cool about the session. screened a movie in the session! What’s special about the movie is that its an Open Movie! Yes, we at GLOSS seek out for such wonderful products. The movie was completely rendered using the Super Computer service offered by Sun Microsystems through Also, this movie was completely created using an open source animation software named Blender. I will try to upload the video here as soon as I can. Enough of the general talk, lets get down to business and learn about Cluster Computing shall we?

Cluster Computing and High Availability

Consider yourself to be running a big service provider like GOOGLE or Microsoft. You have your server running at your office, suddenly one day, the server crashes for unknown reason or some natural disaster strikes and your office gets demolished (sorry for being so optimistic! :-P). Your services like mail, chat video sharing will stop suddenly and users will not be able to access it until you correct the problem. This may take a very long time but your users cannot wait so long. They will migrate to some other service provider and your business will end up craching down hill. Here is a scenario. You have a server running some application connected to a storage device where the entire data of your serivces are stored. Now, if the connection between the server and the storage or the connection to the server is cut, imagine the kind of damage your business can suffer. This is where Cluster Computing comes in for the rescue. You have some servers spread across geographically running for your services. If disaster of any form strikes at any of these nodes, in cluster computing, the node fails over some other node. In plain English, the services running on that node will be copied to some other node and the service will continue running almost immediately. So the user will not know about the server crash and he will the service uninterrupted as usual. This powerful concept is called Cluster Computing. Most people confuse it with Grid Computing. In grid, you have more than one computer running as a single computer. Here you have individual computers running individually. If any node crashes, the service will be shifted to some other node. Lets get more technical in cluster computing.

How the Cluster is Formed and Maintained?

Clusters are formed by using some cluster creating tools like OHAC, by writing stuff called agents and distributing your servers. Each node in a cluster gives out some signals similar to hearbeats. So, they are named Heartbeats. The nodes and the cluster tool identifies the other nodes in the cluster by this heartbeat. If a node fails to give out heartbeats, it is considered to have been dead and its services are shifted to some other node.

Components of a Cluster

Now that you know how a cluster works, lets look deeper into them and understand the different components that are essential for a cluster to work.

1. Quorum :
You need a minimum of n/2 +1 nodes for a cluster to work.

2. Cluster Infrastructure : The cluster infrastructure is the software which is used to run the cluster like OHAC and also the servers and the storage devices which are all interconnected. Now, the cluster software decides to which node the service running should fail on in case of a disaster.

3. Agents : Usually, we use applications which we use are not meant to be run on multiple computers in the same time. For instance, your real player is not meant for a multi computer usage. These agents take care of this problem and make such software run on multiple computers. These programs act as a communication bridge between the cluster infrastructure and the service. In case of a disaster, they pick up certain parameters from the service application and pass it to the cluster infrastructure which will take care of the rest of the stuff.

4. Application : This is the service which is running on a server. Eg: Mail service. In case of a disaster, the cluster makes sure that this application keeps running safely for the user by failing over some other node.

A Special Case of Failure

Consider this case, your servers are running fine but then suddenly, the network cable for one of your node gets cut but the server which got isolated from your network can still access and write data to your storage device. We don’t want this do we? So to tackle this problem, there was another concept introduced called Data Fencing. By data fencing, you can protect your storage devices to be accessed and changed only by the nodes in your cluster. This Data Fencing is a very big and interesting topic which will be dealt in some future session of GLOSS.

Getting OHAC

You can get the source code for OHAC here Download it, build it and create your own clusters. When you start using OHAC, try to contribute to their project using the same link as above.

I have tried my best to explain the concept of Cluster Computing in a simple way and also I have explained only the most important components of this area. My advice is, not many people in this world are into cluster computing so its better to act fast and make your moves in this field.

My sincere thanks to

Kumar Abhishek (for the session on Cluster Computing and for giving me his presentation slides)
The Photography Wing of GLOSS (trust me, they have did a really good job this time)
and to you! (for reading through my blog :-))