Could not increase number of max_open_files to more than… (Solution)

A quick solution to the warning “Could not increase number of max_open_files to more than” when starting MySQL or MariaDB. For some background, read How MySQL Opens and Closes Tables. Here’s an excerpt: “The table_open_cache and max_connections system variables affect the maximum number of files the server keeps open. If you increase one or both of […]

Free vs. Available Memory in Linux

At times we will need to know precisely how our Linux systems use memory. This article will examine how to use the free command-line utility to view memory usage on a Linux system. In doing so, we will clearly define the difference between free vs. available memory on Linux systems.   Free vs. Available memory […]

Finding Linux Compatible Printers

Here’s all the info and links needed to find printers or all-in-one printers that currently support Linux. If you don’t want to spend hours comparing printers, have a look at my recommended Linux compatible printers. This is the promised update as per the comments section below, sorry about the delay! Fixed broken manufacture product links and replaced […]

PHP Performance: Additional CPU cores vs Faster CPU cores

Some time ago, I received an email from a client experiencing slow performance issues with a LEMP (Linux, Nginx, MySQL, and PHP webserver). During a full audit, I found that the server’s load average was pretty low (see above screenshot). However, the website was indeed very slow. There were some misconfigurations, but one of the […]

50 Top ‘Internet of Things’ Security Solutions

A couple of months back, I decided to maintain a list of companies that offer IoT (internet of things) security tools and solutions which you can find below. Feel free to share your solutions, feedback, and tips for securing IoT devices. In the future, I will update this list continuously. A few key questions arose […]

Linux top: Here’s how to customize it

The top command – referred to below as Linux top – is a command on Unix and Unix-like systems such as Linux, which provides a dynamic real-time overview of a running system. It can display system summary information and a list of processes or threads currently managed by the Linux kernel. The types of system […]

PHP-FPM tuning: Using ‘pm static’ for max performance

Let’s take a very quick look at how best to set up PHP-FPM for high throughput, low latency, and more stable CPU and memory use. By default, most setups have PHP-FPM’s PM (process manager) string set to dynamic and there’s also the common advice to use ondemand if you suffer from available memory issues. However, let’s […]

Are you measuring Linux web server memory usage correctly?

This article was first published in 2014. Afterwhich, there was a welcomed change to the Linux kernel in 2016; as mentioned in the 2017 article: Does your Linux server need a RAM upgrade? Let’s check with free, top, vmstat and sar. As outlined here, memory is now marked as available by the Linux kernel: “Estimation of […]

SCP Linux – Securely Copy Files Using SCP examples

This post includes SCP examples. SCP or secure copy allows secure transferring of files between a local host and a remote host or between two remote hosts. It uses the same authentication and security as the Secure Shell (SSH) protocol from which it is based. SCP is loved for its simplicity, security and pre-installed availability. […]