Alliance BroadBand Connectivity Issues in Kolkata

February 15, 2018 at 6:43 am (Uncategorized)

I have been on Alliance Broadband for a few months and I noticed that every 30 minutes or so the connection would break and would require re-connecting. I looked into the router settings and realised that the Alliance provided DNS server is the culprit. It is probably an ill-provisioned server which is unable to take the incoming query load and hence requests start failing.

The solution is to replace the primary DNS server on the router settings with Google DNS server or any well known public DNS server. Keep the Alliance provided DNS as the secondary nameserver. That will solve the issue.


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My harrowing German student visa interview experience

February 20, 2017 at 4:42 pm (Uncategorized)

This is a complaint regarding the unprofessional and rude behaviour I faced from the vfs staff today during my visa interview.

My web reference number is NDEM/040117/7698/01 and I applied for a student visa at the Delhi German embassy.

My interview was scheduled at 14:00 hours. I reached on time. I was sent to counter number 2 which was handled by a young woman of Indian origin. When I reached she was handling a person from Punjab, a 21 year old male. He had a lot of missing documents and had a hard time following her instructions. He also did not have a printed application form. All of this led to a lot of time wastage which made the lady handling the counter visibly upset and disturbed.

When after almost 30 minutes my turn came it turns out I too did not have a printed application form at which she again lost her temper and started saying things like “what is wrong with people today, this is not a joke, this is a visa interview”. She then handed me a printed form to fill up and said “fill this up within 5 minutes”. Having been put under pressure I filled up the first page and asked her if I should fill up the rest of the pages as well at which she retorted “What kind of question is that? Isn’t that obvious?”
I proceeded to fill up rest of the form. There were fields which I was not sure about and things I did not remember clearly but I did not have the courage to ask her for help since she was behaving extremely rudely. I must have made some mistakes in the process. She then said “Why can you not fill up a form properly? Is this a joke?”. She then saw a slight smile on my face, which is just how a gentleman behaves in times of distress and nervousness at which she said “You have a smile on your face, I do not know what it means.”.

At this point a German gentleman standing behind her intervened and asked her what the problem is. He politely told me that “Sir we do not accept incomplete forms” at which I said I am sorry and that I will fill it up promptly. I felt reassured by his behaviour.

She then asked me if I have brought money. I said Yes. She asked how much. I said enough. She then said “Are you lying?” I was once again flabbergasted at her manner!

I hope this complaint finds its way to the right person who can tell her that she is doing disservice to the German diplomatic community. She needs to learn to keep her calm under all circumstances and not behave like a child, and not treat adults like children either.

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Ubuntu 15.10 on Macbook Air 7,1 2015 model

February 28, 2016 at 6:19 pm (Uncategorized)

There is comprehensive guide to installing to installing Ubuntu 14.xx distros on Early 2013 Macbook Airs (6.x and before) on the official Ubuntu wiki here.

I recently purchased a 2015 Macbook Air (7.1) which has some new hardware, and I ended up with a disturbed Ubuntu install even after following the wiki above. I spent a few days getting everything to work properly. Here are the problematic parts and the solution:


sudo apt-get install bcmwl-kernel-source

You can use 3g from your phone through USB tethering to get internet connection for the above step, or use an ethernet adapter if you have one.

Graphics Driver

Download and install the Intel graphical driver installer from

Then reboot.

Screen brightness

It is a common problem for Ubuntu across Macbook Airs that after suspend and resume, the screen brightness gets locked to either 0% or 100%. You can not control screen brightness between these 2 values.

First edit /etc/default/grub to have this line:

GRUB_CMDLINE_LINUX_DEFAULT=”quiet splash pci_aspm=force i915.i915_enable_fbc=1 acpi_backlight=native”

Then run:


Then you need to build from source

# git clone
# cd mba6x_bl/ && make && make install

Make sure the module is loaded at boot time. E.g add "mba6x_bl" to /etc/modules
You also need to configure i915 to hand over the backlight control to mba6x_bl. I added this to my /etc/X11/xorg.conf:

Section "Device"
        Identifier      "Intel Graphics"
        Driver          "intel"
        Option          "Backlight"     "mba6x_backlight"

Now reboot and you should have working brightness even after suspend/resume.

I did not find any other hardare related issues that is not mentioned on the official Ubuntu wikis.

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rabbitmq UI configuration in nginx

May 14, 2015 at 7:59 am (Uncategorized)

We faced a weird issue when we proxied nginx to rabbitmq admin UI. Certain URLs would not open and would say “Not Found”. The issue is that for some URLs rabbitmq sends a %2F control character in the URL which gets scrubbed before it reaches nginx.

The fix for this is the following in nginx:

location ~*  /api/(queues|exchanges)/(.*) {



Hope it helps someone.

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My RTI with Delhi Transport Corporation

November 21, 2014 at 6:58 pm (Uncategorized)

Delhi is unique in many ways. One which caught my eye is the fact that bus conductors in Delhi remain seated while passengers crowd around him to get tickets. This is quite different to how things happen in other cities I have been to.

This behaviour causes several problems. I saw a woman with a child struggling to find her balance waiting for the conductor to give her a ticket. I found it quite shameful.

So I did an RTI asking which clause or which order, if any, mandates this permanent seating behaviour by conductors. (RTI No, TR/SH/RTI/ID-1917/2014/4983).

The RTI mentiond a 1990 order passed by the then Surface Transport secretary V. Sankaralingam. Apparently the conductors have always had a seat but in 1990 they went on a strike and as a punishment to them the previous transport minister banned conductors from even having a seat! After ministry change the decision to restore the seats were taken.

Now this reply does not actually answer my question at all! I am not against conductors having a seat to themselves, which all conductors have in other cities as well. The reply did not mention why they remain seated throughout the journey.

So I will now write a letter to the Surface Transport Ministry.

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RTI with Northern Railway

May 13, 2014 at 7:44 am (Uncategorized)

About a month back I filed the following RTI. Today I received a reply as follows:

1) How long have the escalators been out of action?

Ans: The 2 escalators have been out of order since 20.11.2013 and 20.01.2014 respectively.

2) What caused this breakdown?

Ans: The codel life of the escalators has been completed.

3) What action has been taken so far to get them back in working state?

Ans: The escalators will be replaced by new one for which estimate is under vetting from finance.

4) Which department of the railways is responsible for the maintenance of these escalators?

Ans: The escalators are being maintained by Electrical/G Dept.

5) How much money approximately will it cost to get these escalators fixed?

Ans: The cost of a new escalator is Rs 1 Crore.

6) By what date can one expect these escalators to be fixed?

Ans: Expected by end of November 2014.


My observations:

1) It is going to take a full year for the railways to fix 2 escalators.

2) They are not actually fixing the broken part, They are buying new escalators.

3) Each escalator costs Rs 1 Crore, which to me seems like an absurdly high amount.

4) The financial estimate for replacing the escalators is still pending with finance department.


I must say I am astonished at how casually they are treating this whole thing when a working escalator at the New Delhi railway station is surely not too much to ask.


EDIT on 20 May 2014:

I had also filed a separate complaint at the public grievance portal ( registration number MORLY/E/2014/02961. Apart from that I had filed a complaint on The 2nd complaint carried my Greater Noida Address. I currently live in Bangalore with my wife, whereas my parents and my brother live in the Gr Noida address.

My mother today informed me that they have a received a letter from the Chief Engineer of Railways, which was basically a copy (cc) of a letter that he sent to the Electrical Engineer incharge of the escalator, asking him for a report on why the escalators have been out of action for so long. I have not seen the letter myself, but I should get a copy of it tomorrow and as soon as I do I shall put it up here in this post.

One thing I noticed is that not only are my complaints being replied to, they also send me copies of internal communication, which is really good.



I am happy to report that the 2 escalators in question have been replaced with new ones by Indian Railways! I am glad that lakhs of people will benefit from this.


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My journey with the bamboo flute so far

September 26, 2013 at 2:03 pm (Uncategorized)

EDIT: I found that Subhash Thakur is selling flutes at a decent price on

I picked up the flute about 2 years back when I saw a friend of mine in Gurgaon playing it. I had tried some other instruments earlier (tabla, drums, guitar) but the simplicity of the flute moved me. It was just a bamboo with holes. All you need is practice! I liked the idea.

I was encouraged by the fact that I could produce a clean sound right away. I knew I could make progress.

I started playing by ear. That means I could listen to a song and then slowly reproduce it on a flute, note by note. I can do this probably because I have had musical training in childhood (being from a Bengali family). The way to play an instrument is to learn how to play the lowest note and then the highest note. All songs lie somewhere between these two places 🙂 For people who can not do this right away it only requires some practice, patience and sometimes a good teacher.

The best way to start is to play sa re ga ma pa dha ni sa on the flute. Watch YouTube for lessons on how to do it. Then play more complicated permutations and combinations of the same sargams. Later you can look for notes for popular songs. It is best though if you can play songs just by listening to them but it may take you some time to reach there. You brain needs some time to learn which note lies where on a  flute.

I loved the fact that a decent flute can be bought for no more than 400 – 500 Rs in India. Other instruments are way more expensive. If you are in Delhi you should head over to Daryaganj, Netaji Subhash marg. There are several music instrument shops there. Saskhi Musicals is the one shop known for its flute collection. You should just walk up to the shopkeeper there and tell him you are a novice and your budget. He will help you accordingly. You should initially purchase a medium size flute, like a G medium (would not recommend very small flutes) on which you can cover all the six holes with your fingers comfortably. Then move up to larger flutes gradually.

The best quality flutes are not available in shops. They are sold to foreign customers in dollars and Euros. That is quite a tragedy. There are a handful of shops like Sakshi Musicals who do keep excellent quality flutes as well. The shopkeeper there will only show them to you if you can first show him that you can play well 🙂

After I moved to Bangalore recently I started looking for better flutes. You will find any flute player’s house full of flutes because we are addicted to buying flutes, wherever we go! I found a flute maker’s advertisement on I met him. He showed me some concert quality flutes which cost about Rs 5000 on an average. Generally the E natural scale flute is played in concerts and it requires a few months of practice to be able to close all the holes properly. This is the flute that I normally play today.

There are 2 shops in Bangalore that I know keep good quality flutes. One is in JP Nagar 1st phase and the other in MG Road.

In general larger flutes have a deeper sound (good for serious, sad, haunting songs) while smaller flutes have sharp/shrill sound (good for folk). You should look for something in the middle.

Gradually I felt that I had reached my own limits of playing and I needed a teacher. My search for a teacher was made difficult by the fact that I was in South India but I wanted to learn Hindustani Classical on the flute. That is the intersection of 2 sets, hindustani classical and flute. My primary criterion was that the teacher must not attach religious practices to his teaching. I absolutely hate that.

After much searching I found Vaman Joshi who satisfied all my requirements for a teacher perfectly. He shared much of my views on music and its direction and I love talking to him in general. (Found his listing on as well 🙂 )

The first day I went to his place I told him my grip is wrong and I need to learn music theory. He asked me to play a few songs and identified the basic problems. Then he started giving me exercises so I could adjust to the new grip. I am still working on those exercises.

The first 30 minutes of the class we practice the exercises. Then for 15 minutes we talk about music theory and life in general. Then last 15 minutes we play some songs from Indian cinema together.

It has been an amazing experience so far.

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Amazon AWS case study for Gazemetrix

May 16, 2013 at 10:51 am (Uncategorized)

Gazemetrix allows brands to find out when pictures of their products appear on social media. We process millions of images everyday using image processing algorithms and match these images against a set of logos. This is a compute and IO intensive process and we decided Amazon would be the best platform to build our infrastructure on. Amazon has also been very generous to provide us with credits from time to time to make sure that we as a young startup can focus on our customers and buiness properly.

We use the following Amazon AWS services:

  • EC2
  • S3
  • CloudWatch
  • Route 53
  • SES
  • SNS
  • Developer level paid support

We are a fan of spot instances of Amazon. They are a cheap way of doing large scale compute intensive work. We use the Amazon Auto-scaling API to spawn and terminate spot instances based on current CPU utilisation of the auto-scaling group. This roughly translates to “Scale up if more images are coming and scale down when lesser images are coming”. We get many more images during daytime in the US/Europe region and during that period our image processing cluster has the maximum number of instances spawned. Here is a graph to depict how the incoming image load varies and also our churn rate, and number of spot instances spawned at any given time:


So as the above graph demonstrates, we use somewhere between 50 to 150 spot instances at any given time. Weekends are busier than weekdays since people like to take photographs when they are having fun.

We have five different auto-scaling groups. Each auto-scaling group takes care of one part of the image matching process. One group does its job and passes on the result to the next group via redis. We would have liked to use ElasticCache someday but we like the in-memory sorted sets that redis provides us with. The day ElasticCache provides similar data structures, we will probably transition to it.

We have written custom monitoring scripts which send data from the infrastructure to CloudWatch. We use SNS to get alerted when something important happens. For example, the load on the redis queues is something we need to keep in check, and we plot it and also send out alerts via email and SMS to people who need to take care of it immediately:


We have, till date, processed 320 million images on Amazon:


We use c1.xlarge machines for the image processing groups. We like them because they have good processing power yet decent amounts of RAM.

Apart from the image processing core, we also host a web server (, a mongo DB server and a redis server. All of these machines have pretty generous amounts of RAM. Both redis and mongo are very memory intensive applications. We use m2.2xlarge and m2.4xlarge machines for them.

We use S3 to store training logos to be used by the image processing core, Route 53 for our DNS requirement and SES for sending out alerts to our team and mail reports to our customers. We also use IAM to manage user logins, and follow MFA device policy to secure our logins. All of this is provided by Amazon. Here is a look at how good Amazon SES is:


We played around for a while with some of the GPU based instances which Amazon provides. GPU based instances are great for image processing work, but we are yet to deploy it into production. We also spent some time playing around with the newly launched OpsWorks to do rapid deployments of the image processing AMIs and it looks pretty neat.

We have been particularly impressed and thankful with Amazon Developer level paid support plan. The responses from the team have been prompt, courteous and technically superior. Having spent around a year at my previous company working with the support team at RackSpace, I can say for sure Amazon is far ahead in this regard as well. We actually had a big problem with inflated network transfer bills for a couple of months. It took us some time to figure out that the bill was due to having our redis server in a different availability zone compared to the rest of image processing groups. The Amazon team not only helped us to diagnose the problem, but also reversed much of our network transfer charges in good faith. 

Would like to end the post saying a big thanks to Amazon for not only being an extremely professional and performing player in this field, but also looking out for younger startups like us.

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Purchasing Bansuris online

May 2, 2013 at 11:45 am (Uncategorized)

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May 1, 2013 at 4:58 pm (Uncategorized)

I have always been the worst person to the people who love me most. I think there is an evil component in me that seeks release from time to time and people who love me are the only ones I dare release it on.

Others would simply kick my ass in return.

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