How to Kill Inactive SSH Sessions

So, you’ve been disconnected from your server a couple of times which resulted in inactive ssh sessions. You know this because when you use the “w” command, you see something like the following… 22:47:28 up 315 days, 21:09, 2 users, load average: 9.04, 8.17, 7.30 USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT root pts/0 ipxxx-xxx-xxx-xxx 23:54 […]

MySQL Performance: Stop hoarding. Drop unused MySQL databases

Last year, I was assisting a new client in addressing MySQL performance issues. There were several areas where MySQL performance issues were addressed. One issue overlooked for several years prior to our communications, was that of keeping around unused databases. Over 15GB of unused MySQL data – a mix of MyISAM and Innodb tables – […]

How to fix: At least xMB more space needed on the /boot filesystem

Updated: Aug 13th 2018 List all installed kernel packages with: yum list kernel The kernel in-use will be underlined and cannot be removed: Now to remove unused kernels, install the yum-utils package and use the package-cleanup util: yum install yum-utils package-cleanup –oldkernels –count=2 To make this permanent, edit /etc/yum.conf and add the following line: installonly_limit=2 – – – – – […]

Linux: ncdu and mc to manage large directories

Creating, modifying and deleting files are common tasks performed in any operating system. Even more so by Sysadmins, Developers and Programmers. For the most part, these tasks are fast enough when managing a handful of files. However, on Linux and especially with servers, you may at sometime have to manage millions or even billions of […]

81% of all Smartphones are powered by Linux

Update July 19th 2018: Now 85% as per latest report. No, I didn’t use a misleading blog title. Smartphones powered by Linux are in fact dominating the smartphone market. A few of you may be scratching your heads at this point (stop that, you’ll go bald) while others are filled with that Sound of Music […]

Linux top: Here’s how to customize it

The top command – referred to below as Linux top – provides a dynamic real-time view of a running system. It can display system summary information as well as a list of processes or threads currently being managed by the Linux kernel. The types of system summary information shown by Linux top command and the order […]

Nginx tuning tips: TLS/SSL HTTPS – Improved TTFB/latency

As of 30th June 2018, the PCI Security Standards Council requires that support for SSL 3.0 and TLS 1.0 be disabled. TLS 1.1 or higher must be used and TLS 1.2 is strongly recommended. In addition, starting this July, Google Chrome will begin to mark HTTP web sites as “not secure”. Over the past few years, […]

Free Linux Server Monitoring and APM solutions for SysAdmins

Today’s software applications require developers, testers, and SysAdmins to work together (DevOps) more seamlessly than ever before. A single line of code or poorly configured service can negatively impact your application’s performance, causing crippling slowdowns for end-users. This is where application performance monitoring (APM), comes in. APM is also referred to as application performance measurement or application performance management. […]

How to upgrade to PHP 7 on RHEL/CentOS

TL;DR = Upgrade to PHP 7 using Remi’s RPM repository – PHP Configuration wizard. Red Hat Enterprise Linux (RHEL) is a Linux distribution developed by Red Hat targeted toward the commercial market. Red Hat uses strict trademark rules to restrict free re-distribution of its officially supported versions, but still freely provides its source code. Third-party derivatives […]

htop and top Alternatives: Glances, nmon

Previously we took a look at top, atop and indirectly (due to it’s popularity as top’s alternative) htop (the last screenshot on this page). But are there other alternatives worth looking at? As it pertains to system health and performance, this is largely a matter of preference regarding what data is most important to you. We […]