lev_lafayette's blog

Drupal/MySQL Authentication Error

Yesterday I noticed that a number of Drupal websites I look after were down, and it was a pretty interesting error message:

MYSQL ERROR 2049 (HY000): Connection using old (pre-4.1.1) authentication protocol ref used (client option 'secure_auth' enabled)

Using Live Linux to Save and Recover Your Data

There are two types of people in the world; those who have lost data and those who are about to. Given that entropy will bite eventually, the objective should be to minimise data loss. Some key rules for this backup, backup often, and backup with redundancy. Whilst an article on that subject will be produced, at this stage discussion is directed to the very specific task of recovering data from old machines which may not be accessible anymore using Linux.

Notes on Installing Ubuntu 20 VM on an MS-Windows 10 Host

Some thirteen years ago I worked with Xen virtual machines as part of my day job, and gave a presentation at Linux Users of Victoria on the subject (with additional lecture notes). A few years after that I gave another presentation on the Unified Extensible Firmware Interface (UEFI), itself which (indirectly) led to a post on Linux and MS-Windows 8 dual-booting. All of this now leads to a some notes on using MS-Windows as a host for Ubuntu Linux guest machines.

The Net Promoter Score: A Meaningless Flashing Light

Almost two years ago I made a short blog post about how the Net Promoter Score (NPS), commonly used in business settings, is The Most Useless Metric of All. My reasons at the time is that it doesn't capture the reasons for a low score, it doesn't differentiate between subjective values in its scores, and it is mathematically incoherent (a three-value grade from an 11-point range of 0-10).

Why Computers Lie Badly At Alarming Speed and the unum Promise

The translation of arithmetic to physical hardware with using the IEEE standard employed numerical representation is fraught with difficulty. As is well known by any who have used even a pocket calculator, computer processors are imprecise with dangerous rounding errors, which vary on different systems. Further, the standard representation method, IEEE 754 "Standard for Floating-Point Arithmetic" (1985, revised 2008), is extremely inefficient from an engineering perspective with increasing physical cost when additional precision is sought.

International HPC Certification Forum and AU-NZ Contributions

High Performance Computing (HPC) is the most effective method to process increasingly large and complex datasets, making them increasingly critical for research organisations. Researchers wanting to use HPC resources often start with low levels of skills in using those systems. Despite this situation, educational programmes coming out of well-informed user needs analysis and/or a widely acknowledged set of required skills, capabilities and knowledge are rare.

How Niantic is Killing Ingress

For the past several years, I've been an active player of Ingress, a game where two competing factions play a sort of "capture-the-flag" of public locations of note using an augmentation of Google maps. The game, the precursor to Pokémon Go, and Harry Potter: Wizards Unite, has had its fair share of issues over the past six years. But on July 19, 2019, a death knell was sounded by the very company that produces the game; they forced players (albeit temporarily) to adopt the new interface, Ingress Prime, which is passionately hated by the overwhelming majority of the game's players, and for good reason. The interface is a radical change to the old version, has distracting effects, issues with visual accessibility, and is cumbersome to use. These issues have been raised by the player community for months now, but have largely fallen on deaf ears. Why is this? Why would a game company be so inattentive to the player base?

It is perhaps not so well known, but Niantic started off as a Google project, working on the Field Trip alogorithm, which would push information to users on what the algorithm thinks you might be interested in, and with integration into Google Glass. There's a fascinating unlisted video on Youtube, with an astounding 22 million views, where you basically witness in all of two and a half minutes of how a person is turned on a thoughtless robot, the ideal consumer. Of course, such an algorithm can't make such decisions randomly, it has to know where a person goes, what their habits are and so forth. Trying to find out this information by surveys and the like would be onerous to the extreme; but Google Location Services can provide that data, and players will willingly give up such privacy for the entertainment of an Augmented Reality game, whether it is Ingress, Pokémon Go, or Harry Potter: Wizards Unite.

Gurobi Installation and Tests on a HPC system

Gurobi is an optimisation solver, which describes itself as follows, thus explaining it's increasing popularity:

The Gurobi Optimizer is a state-of-the-art solver for mathematical programming. The solvers in the Gurobi Optimizer were designed from the ground up to exploit modern architectures and multi-core processors, using the most advanced implementations of the latest algorithms.

The following outlines the installation procedure on a Linux cluster, various licensing condundrums, and a sample job using Slurm.

Easybuild: Building Software with Ease

Building software from source is necessary for performance and development reasons. However, this can come with complex dependency and compiler requirements, which have to be explicitly stated in research computing to ensure replication of results. EasyBuild, originally developed by the Julich Supercomputing Centre, the University of Gent, and the Texas Advanced Computing Center, is a tool that allows the building of software with ease, managing the complex dependencies and toolchains, and integrating by default with the Lmod environment modules system.

Praise-Singing Poppler Utilities

Last year I gave a presentation at Linux Users of Victoria entitled Being An Acrobat: Linux and PDFs (there was an additional discussion not in the presentation about embedding Javascript in a PDF and some related security issues, but that's for another post). Part of this presentation was singing the praises of Poppler Utilities (named after the Futurama episode, "The Problem with Popplers").


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