Analyze Your Website’s TTFB (Time to First Byte)

Have you improved load time of your websites and web applications recently? Or, maybe your web store or other web app is now slower to respond as you’ve added more features or due to data growth? The time it takes for your web applications to respond when users visit, is more important than ever before! […]

20 Top Server Monitoring & Application Performance Monitoring Solutions

UPDATE: 50 Top Server Monitoring & Application Performance Monitoring (APM) Solutions Last Updated: Nov 23th 2018 – Fixed broken links. (including defunct, mergers, acquisitions, or changed links) Back in September I wrote about an article than touched on the subject of server performance monitoring.  Then just last month a LinkedIn connection asked: “I am using New Relic to monitor […]

MySQL Query Cache for Performance, Avoid This When Tuning

Update: MySQL query cache is deprecated as of MySQL 5.7.20, and is removed in MySQL 8.0. – One of the most misconfigured MySQL performance features, is MySQL query_cache_size. This post references a web server with 32 gigabytes of RAM where the existing config had MySQL’s query cache size set incorrectly to 4 gigabytes. The thought behind it seemed […]

Replacing Cloudflare with CSF Firewall

November 5th 2018 update: I’ve updated this article (the install URL and other minor fixes/improvements). I replaced Cloudflare and thus also Cloudflare Argo with KeyCDN + local firewall and server hardening for this blog as of June 2018. However, do support clients who use Cloudflare and still highly recommend it.  2017 update: With the recent Cloudflare “Cloudbleed” data leak. […]

htop: Here’s how to customize it

htop is an interactive system-monitor, but also a process-viewer, process-manager, strace tool and more. Sysadmins may opt to use htop in cases where Unix top does not provide enough information about system processes. htop uses a cursor-controlled interface for sending signals to processes. Just one example where this comes in handy: you don’t have to type […]

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 […]

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 […]