How Do You Troubleshoot HAProxy when The Service Seems to Work on The Back-end but You Cannot Use It from The Front-end (via a web browser)?

Problem scenario
Your HAProxy server seems to be up, but it is not working (as a load balancer or otherwise).  You use nmap or a PowerShell port testing program (see “Using PowerShell Version 3, How Do You Determine If a Port Is Open for a given IP Address?“).  You find that there is activity on port 80 and/or the traffic is not blocked over port 80. 

A List of Books About Website Performance, High Availability and Scalability

The Art of Scalability: Scalable Web Architecture, Processes, and Organizations for the Modern Enterprise (2nd Edition) by Martin L. Abbott and Michael T. Fisher 
Cloud Computing for Complete Beginners: Building and Scaling High-Performance Web Servers on the Amazon Cloud by Ikram Hawramani
Even Faster Web Sites: Performance Best Practices for Web Developers by Steve Souders
Getting Started with Memcached by Ahmed Soliman
High Performance Drupal: Fast and Scalable Designs by Jeff Sheltren,

Can SSH Work between a Linux Server and a Windows Client When the Window’s Machine Has Inbound Port 22 Traffic Blocked?

Question
Can SSH work between a Linux server and a Windows client when the Window’s machine has inbound port 22 traffic blocked?

Answer
Yes.  Some VPN tunnels initiated on a Windows machine block inbound port 22 traffic (but not all).  Regardless of whether a firewall or VPN tunnel prevents inbound connections over port 22 to a Windows machine, you can make establish an  SSH connection over port 22 from a Windows machine.  

A List of Informatica Books

Agile Data Warehouse Design: Collaborative Dimensional Modeling, from Whiteboard to Star Schema by Lawrence Corr and Jim Stagnitto
Applying SOA Principles in Informatica: Applying Service Oriented Architecture (SOA) principles in Informatica PowerCenter by Mr Keshav Vadrevu
INFORMATICA INTERVIEW QUESTIONS & ANSWERS: Hands on tips & questions to crack the interview. by ks
Informatica Powercenter 9.x ETL Developer Including 20+ Hours of Online Video Tutorial by Rudrani Josh
Informatica PowerCenter – The Complete Reference: The one-stop guide for all Informatica Developers by Mr Keshav Vadrevu
Learn Informatica in 1 Day: Definitive Guide to Learn Informatica for Beginners by Krishna Rungta
Learning Informatica PowerCenter 9.x by Rahul Malewar
SAP and Informatica PowerCenter Internal Tables: Consultant Guide by Mirzakhmet Syzdykov

For a DevOps ETL quiz,

A Long List of Bioinformatics Books

The 2011-2016 World Outlook for Bioinformatics by Icon Group International
The 2016-2021 World Outlook for Bioinformatics by Icon Group International
Adjusting Autonomy in Multi-Agent Bioinformatics Integration Systems: A criticality-based framework by Konstantinos Karasavvas
Advanced Python for Biologists by Dr Martin O Jones
Advance in Structural Bioinformatics (Advances in Experimental Medicine and Biology) by Dongqing Wei, Qin Xu, Tangzhen Zhao and Hao Dai (Editors)
Advances in Bioinformatics and Its Applications – Proceedings of the International Conference (Series in Mathematical Biology and Medicine) by Matthew He,

With Linux the Export Command Works Fine from the Terminal but Not in Scripts, How Can Scripts Provide the Correct Bash Environment Variables?

Problem scenario
EXPORT works when you use it interactively from the command prompt (e.g., bash prompt).  But when you use EXPORT commands in shell scripts, they do not have the desired effect.  You have a Linux script that sets environment variables.  You do not want to log off your terminal or desktop session after the script runs to get the environment variables.  How do you change environment variables via a shell or bash script in Linux without logging off and logging back in?

How Do You Update a BIOS on an HP ProBook Laptop Computer When the Directions Do Not Work?

Problem scenario
You cannot update BIOS on an HP ProBook (a laptop) computer.  You tried following two different update instructions, but they both failed.  You tried using HPBIOSUPDREC (by double-clicking the download file) and “following the on-screen instructions.”  This resulted in an automatic boot to BIOS just to see an error that says “Unable to open BIOS image file.”  You tried installing the HP System Software Manager (SSM).

A List of SAP Books

Ever wanted to speak Sapanese?  The initialisms and acronyms can be overwhelming.  Many people find classes to be poor ways of learning.  Here is a list of books that may help you learn about SAP.

105 SAP Security Interview Questions with Answers & Explanations by J Jerome and S Kaur
110 SAP SCM-Order Fulfilment (SD) Interview Questions: with Answers & Explanations (Volume 2) by S Kaur and Kristine K
1000 SAP ABAP INTERVIEW QUESTION &

How Do You Tell If You Have a 32 Bit Version of Linux or 64 Bit Version of Linux?

Problem scenario
You want to install Docker on Linux.  But you need a 64 bit version of Linux.  How do you determine if your operating system is 32 bit or 64 bit?

Solution
Run this script:

#!/bin/bash
os=$(uname -m | grep -i x)
if [ -z “$os” ];
then
  echo “The OS is 32 bit.