In my last article I looked at how the Linux kernel manages memory. This article covers the memory information shown in the free and top…
Category: Server management
Understanding memory on Linux servers
Memory on modern operating systems is a complicated topic. This article covers what memory is and how the Linux kernel manages memory. The next articles…
How to use the sar utility
The sar utility is part of the sysstat monitoring tools. sar collects a huge amount system activity data. This includes data about CPU and memory…
How to install and configure sysstat
Linux servers come with lots of system monitoring utilities preinstalled. However, RHEL-based servers don’t include the sysstat collection. Among others, sysstat includes sar and iostat.
Log rotation on Linux
In my article about logging on Linux I looked at how log rotation works with systemd-journald. This article looks at how log rotation works for…
Logging on Linux
Logs are important. They provide a wealth of information about what is happening on your server, and when something goes wrong you are likely to…
Common SMTP errors
When you send an email your email client (Mail User Agent) connects to the mail server. This article describes the most common connection errors, and…
Email ports and SSL/TLS
Servers use ports to listen for specific types of connections. This article looks at the most common email ports for POP3, IMAP and SMTP. I’ll…
Understanding email routing
Often, it’s easy enough to understand why an email error happened. For instance, the error “incorrect authentication data” means that the email address and/or password…
The inherited PHP version on cPanel servers
cPanel servers use a default, or inherited, PHP version. The default version is automatically applied to new cPanel accounts you create. This makes it easy…