today's howtos
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The Maildir mail storage format doesn't seem to work well over NFS
There's a relatively widespread view that the Maildir mail storage format is the solution to any issue that one is having with traditional mail message storage. In general I feel that Maildir only solves some problems and makes others worse (although that entry was written in the days of HDDs with very limited IOPS). In our specific environment, we've found that Maildir over NFS to our fileservers is actually pretty terrible once you have a large Maildir folder, one with thousands of messages.
Our IMAP server is Dovecot, which normally automatically supports Maildir format folders if you set one up. Our default folder format is old fashioned mbox format folders (with all messages in one file) and most of our users follow that. However, we have had a very few users who set up Maildir format folders, which are stored in their home directory on one of our NFS fileservers, and then put thousands of messages in those Maildir folders. The observed result on our IMAP server is that them looking at this folder tanked the performance of their mail session and could affect the entire machine's performance.
In this problem's most recent incarnation, this was not because of limited IOPS from HDDs; by that point all of our fileservers were using local SSDs, and mirrored at that. ZFS uses non-linear directories, so directory lookup in large directories shouldn't be a problem and anyway our fileservers have lots of memory and high cache hit rates (and even 10,000 files in a directory isn't large by modern standards). We tried a number of things and investigated in a number of areas, but as near as we could guess, the problem may well be the sheer number of NFS operations that are required to scan a directory and look at things in it. Dovecot normally maintains indexes of folders that mean it doesn't have to touch the folder itself, but maybe it doesn't index Maildir folders or maybe the index was frequently being invalidated for some reason.
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A NixOS kiosk
A kiosk, in the sysadmin jargon, is a computer that is restricted to a single program so anyone can use it for the sole provided purpose. You may have seen kiosk computers here and there, often wrapped in some kind of box with just a touch screen available. ATM are kiosks, most screens showing some information are also kiosks.
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Solene'% : Extending fail2ban on NixOS
Fail2ban is a wonderful piece of software, it can analyze logs from daemons and ban them in the firewall. It's triggered by certain conditions like a single IP found in too many lines matching a pattern (such as a login failure) under a certain time.
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How to Install a New Package Manager in Linux
A package manager is essential for managing and maintaining software on your Linux system. Each Linux distribution ships with a package manager by default. Ubuntu comes with the APT package manager, Arch-based distros have Pacman, and so on.
If you wish to explore other package managers, here's how you can install a different package manager without having to switch to a brand-new distribution.
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How To Install Eclipse with WindowBuilder on Ubuntu
This tutorial will help you install Eclipse with its visual development tool Window Builder. With this, you can develop computer applications in Java programming language rapidly by drag and drop aside from writing code and produce high quality Graphical User Interface (GUI) applications. Now let's install it!
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How To Install GitLab on Rocky Linux 9 - idroot
In this tutorial, we will show you how to install GitLab on Rocky Linux 9. For those of you who didn’t know, GitLab is a free git repository management tool that allows you to create and manage git repositories. With GitLab, you can host your own internal repository for a development team and allow users to host their projects.
This article assumes you have at least basic knowledge of Linux, know how to use the shell, and most importantly, you host your site on your own VPS. The installation is quite simple and assumes you are running in the root account, if not you may need to add ‘sudo‘ to the commands to get root privileges. I will show you the step-by-step installation of GitLab on Rocky Linux. 9.
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How to download Linux Mint 21 - Updated - Real Linux User
It seems from the beginning of time the Linux internet community is discussing, blogging, and vlogging intensively about Linux Mint, one of the most popular Linux distributions. It is extremely popular among both beginners and advanced users, who just want to get things done with their operating systems. So you want to know how to get your hands on one of the most popular, stable, and user-friendly Linux distributions? In this article, which is the start of a complete refresh of all my previous Linux Mint 18 based articles, you will learn how to download the most recent Linux Mint 21. In this article, you will learn how to download Linux Mint 21, so you can create a Linux Mint 21 Live USB stick to try it out in a live environment, or just install it right away.
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How to Unzip a .gz File on Linux (Any distro)
In this tutorial, we’re going to show you how to unzip a .gz file on Linux. These instructions will work on any Linux distro, even on a Mac.
We previously wrote about how to zip files on Linux, so now we’re going to show you how to unzip a GZ file.