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Manage and Configure Kdump Service on CentOS 7 / Red Hat 7

Kdump is a reliable Kernel Crash Dumping Mechanism, in which a crash dump is captured by a second kernel (crash kernel) booted when the main kernel crashes.

This second kernel (crash kernel) uses a small amount of memory for booting and capturing the dump image (vmcore) file. The part of memory reserved by the main kernel is used by the second kernel to boot. Preserving the main kernel’s crash dump is a result of kexec mechanism which allows to boot the second kernel without the necessity of rebooting the system and passing through BIOS procedures.

The time for capturing the vmcore file depends on the amount of the occupied memory during crash. The average time of capturing a 5GB vmcore file is approximately 20-25 minutes.

When the kdump is successfully made during the system crash, a vmcore file is created in a dump location (usually /var/crash/ directory) and next the system reboots. After crash the vmcore file should be analyzed to determine root cause of the failure.

Below we present how to configure and manage kdump service on CentOS 7 / RHEL 7.
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Setup Puppet Master and Multiple Agents on CentOS 7

Puppet is an open-source configuration management tool written in Ruby by Luke Kanies which includes its own declarative language to describe system configuration.

In this tutorial we install and configure Puppet on CentOS 7 based hosts.
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Install Xfce 4 Desktop Environment on CentOS 7

Xfce is a free and open-source desktop environment for Unix and Unix-like platforms which aims to be fast, intuitive, user-friendly and lightweight, while still being visually attractive for user.

In the below short tutorial we will install Xfce 4 Desktop Environment on CentOS 7 system in few steps.
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Install and Configure KVM (Bridge Net Interface) on CentOS 7 / RHEL 7

KVM (Kernel-based Virtual Machine) is a virtualization infrastructure for the Linux which requires a processor with hardware virtualization extension to be able to host guest sytems. KVM is convenient solution to test and try different operating systems if you don’t have a possibility to purchase expensive and power consuming physical hardware.

The below tutorial presents KVM (QEMU) installation and setup along with Linux Bridge configuration on CentOS7 / RedHat7 operating system.
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Install and Configure Elasticsearch Cluster on CentOS 7 nodes

Elasticsearch is a search server/engine based on Apache Lucene. It provides a multi-node distributed full-text search engine with an HTTP web interface and sophisticated RESTful API. Elasticsearch is developed in Java and is released as open source under the terms of the Apache License.

There are several types of nodes in Elasticsearch architecture:

• Master-eligible node – eligible to be elected as Master node, which controls the cluster.
• Data node – holds data and performs data related operations such as search, and aggregations
• Client node – acts as a “router” forwarding cluster-level requests to the master node and data-related requests (such as search) to the data nodes
• Tribe node – special type of client node that can connect to multiple clusters and perform data-related operations across clusters

In this tutorial we will install Elasticsearch Cluster on three Centos 7 based nodes: Master-eligible node, Data node and Client node.
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How to Enable SSH Service in Manjaro Linux

How to enable SSH Server in Manjaro Linux?

Below I present how to enable and launch SSH service on Manjaro Linux, based on CinderCloud VPS, in a few simple steps:
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