It is all about uptime!

System uptime and availability is being increasingly important. Various services are expected to be accessibly at all times. The challenge is to configure and maintain such a system, with minimal downtime, and preferable no downtime at all. At first this sounds like a very complicated task, but breaking it down to its components makes it possible. Configuring and deploying one component at a time, in a redundant way, allows for added complexity in a simple way, which increasingly builds on a stable redundant platform, keeping the redundancy all the way through the component stack. As the system is comprised of redundant components, it is ensured that any component at any time can be taken down for maintenance, without compromising the uptime and availabilty of the system.

The Challenge

Many factors affects such a system, and usually we are not controlling all of them.

• Power outage
• Internet access
• Hardware malfunction
• Software updates

Redundancy for all factors will be very expensive, so here we will focus on the software redundancy, and the physical hardware the software runs on.

Realizing that a redundant system consists of many redundant parts, virtualization naturally comes to mind.

Configure your system

• KVM Host

• KVM Guest

Manage Virtual Domains

• Domain Creation

• Domain Console

• Domain Destruction

• Domain Editing

• Domain Cloning

• Domain Migration

Network Planning

• Network Planning

Configure a Redundant Service

• DNS

• DHCP

• NTP

• GlusterFS

• Corosync and HA-proxy

• Mariadb

• Redis

• Apache

• LDAP

• Postfix

• Dovecot

• Nextcloud

• OPNsense

Configure a Service

• Syncthing

• Minidlna

• Checkmk

Tools

Networking

• nethogs

• bwm-ng

This project is based on the GNU/Linux software packaged by Debian. KVM hosts are running on Buster, guests are for the most part running on Buster. The information provided here will most likely work on other GNU/Linux systems as well. Basic knowledge of GNU/Linux commandline tools, file editing, network etc. is required to use and understand this guide.

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