Posts

Some thoughts on interviewing candidates

One of the most crucial parts of talent acquisition process is the initial round - where you decide if it is worth it to evaluate this candidate on the myriad parameters you might have. This post is not for veterans or hiring managers. This is for people in junior roles who are asked to conduct some parts of the interview process. While I am still a bit low on the totem pole in my organisation - I do get to conduct these initial rounds and some more along the process. I have also observed other people (mostly my peers) in the org doing this. And I wanted to collect some thoughts I have regarding this. 1. Remember who is being evaluated and against what When you are in a position to evaluate someone else, it is only natural to mistake that the evaluation must be in some manner against yourself. Resist that temptation - you are looking at a potential team member and measuring them against yourself leads to nothing good. It will make you blind to some really good qualities of the c
Post a Comment
Read more

High throughput Site to site VPN on commodity hardware - an adventure with Wireguard, bonding and ECMP

At work, I recently had an interesting challenge - we needed a high throughput site to site VPN between two of our co-located DCs. The existing one was not cutting it with the increasing demand for bandwidth every week. Normally I'd opt for the tried and tested IPsec tunnels using strongswan. One of my mentors had done this in the past -  here  is his own write-up. But I wanted to do something different this time. Enter Wireguard, the newest kid on the VPN block. What follows is a brief write up on the attempts to push decent amount of traffic on WG - enough to meet our needs. Here comes the 'interesting' part of the challenge - One side only has 1G LAN - the final ISP uplink is 10G - but the server is only connected to a 1G switch. We need to push more than 1Gbps over the tunnel.  Here is how it looks: +---------------------+                +----------------+ |                     |  Wireguard     |                | |   Site A - 1G LAN   +------------->   Site B - 10G L
1 comment
Read more

A Tale of Apache and Two Congestion Control Algorithms in Linux (With a guest appearance by Openstack and cURL)

Image
Introduction: The shortest intro would be these two cURL times - one for a bare metal server, and one for the Openstack VM - both running the same application, for a specific test URL. Problem: dnslookup: 0.109 | connect: 0.359 | appconnect: 0.000 | pretransfer: 0.359 | starttransfer: 0.624 | total: 6.739 | size: 710012 dnslookup: 0.016 | connect: 0.281 | appconnect: 0.000 | pretransfer: 0.281 | starttransfer: 0.531 | total: 6.958 | size: 710277 dnslookup: 0.000 | connect: 0.265 | appconnect: 0.000 | pretransfer: 0.265 | starttransfer: 0.530 | total: 5.351 | size: 709165 No problem: dnslookup: 0.000 | connect: 0.265 | appconnect: 0.000 | pretransfer: 0.265 | starttransfer: 0.546 | total: 2.168 | size: 705631 dnslookup: 0.015 | connect: 0.281 | appconnect: 0.000 | pretransfer: 0.281 | starttransfer: 0.561 | total: 2.402 | size: 705354 dnslookup: 0.000 | connect: 0.265 | appconnect: 0.000 | pretransfer: 0.265 | starttransfer: 0.546 | total: 2.434 | size: 705485 For more details,
Post a Comment
Read more

Review: This Is Going to Hurt: Secret Diaries of a Junior Doctor

Image
This Is Going to Hurt: Secret Diaries of a Junior Doctor by Adam Kay My rating: 5 of 5 stars Thanks for the recommendation @Gokila! This is a brilliant, light heart-ed read. However, most of the entries in this Diary will sound strange to the Indian reader. Surely Doctors are not this humble, are they? And what is this blasphemy - a patient conversing on equal terms with the doctor? But the other side is not so pretty either. Here in India, we have a different kind of Patient - Doctor relationship than the rest of the world. We simultaneously adore them and loathe them. A significant portion of the population wants their off-springs to try their hand at being doctors - but an equally large portion of the population thinks the doctors conspire to put them through painful and expensive procedures to mint money. (Or worse, to "train" at their expense) We all have read about doctors getting attacked by mobs because someone passed away and the crowd thought it was bec
3 comments
Read more

Virtualization in DC vs AWS

Image
Without getting into the larger debate of private cloud vs public cloud for the organization as a whole, this document tries to give the numbers that let us make a fair comparison in terms of performance - and performance alone between AWS and Private Cloud through Openstack. The initial benchmarking and preparing these numbers stemmed out of the proposed DC migration to a west coast co-located DC at my current employer. The migration did not happen, but it gave us the opportunity to study the performance impact of having our own cloud. One of the gripes that I've had about our colo infra is that we never seem to have gotten grade-A processors. Almost all of the ones were hand-me-down servers or mid-level Intel Xeons, sometime with absurdly low clock speed. The storage side wasn't very brilliant either. This was solved when we obtained a test bed from Dell with the latest and greatest hardware in their lab that we could setup and run benchmarks on. The machine we got w
Post a Comment
Read more

Interesting numbers #1

Interesting numbers will be a section on my blog where I point out statistics that I find are interesting, mildly amusing and provides a new, different perspective. 25% TamilNadu is a key market for Education loans in India, accounting for 25% of all education loans disbursed across the country, amounting to around Rs.20,650 Crores. 1.5Million No. of hectares of forest diverted for non-forest purposes through Forest Conservation Act 1.8Million No. of tribals to be evacuated under a recent supreme court order, under the pretext of preventing protecting forests.
Post a Comment
Read more

On mentorship

Being a mentor is a not an easy thing. There are a lot of things that a mentor has to do, beyond imparting knowledge. To mentor is to mould and sculpt - to recognize there is a permanence to the teaching for better or worse. One of those things is choosing when to intervene as a mentor, and to fix the mess created by your student. My favorite description of the importance of this intervention is captured in a novel by Arthur Hailey, titled Airport. One of the pages has a story about an air traffic controller training a new recruit - "George Wallace nodded and edged closer to the radarscope. He was in his mid-twenties, had been a trainee for almost two years; before that, he had served an enlistment in the U. S. Air Force. Wallace had already shown himself to have an alert, quick mind, plus the ability not to become rattled under tension. In one more week he would be a qualified controller, though for practical purposes he was fully trained now. Deliberately, Keith allowed the
Post a Comment
Read more