Author: Grzegorz Juszczak

Cloud Computing, Storage

Install and Configure OpenStack Mitaka with GlusterFS on CentOS 7

Aug 15, 2016 by Grzegorz Juszczak 14 Comments , , , , , , , , , , ,

integrate openstack with glusterfs storage
OpenStack can use diffirent backend technologies for Cinder Volumes Service to create volumes for Instances running in cloud. The default and most common backend used for Cinder Service is LVM (Logical Volume Manager), but it has one basic disadventage – it’s slow and overloads the server which serves LVM (usually Controller), especially during volume operations like volume deletion. OpenStack supports other Cinder backend technologies, like GlusterFS which is more sophisticated and reliable solution, provides redundancy and does not occupy Controller’s resources, because it usually runs on separate dedicated servers.

In this tutorial we are going to deploy VLAN based OpenStack Mitaka on three CentOS 7 nodes (Controller, Network, Compute) using Packstack installer script and integrate it with already existing GlusterFS redundant storage based on two Gluster Peers.

openstack installation and integration with glusterfs
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Cloud Computing

OpenStack: Unable to Connect to Horizon Dashboard

Aug 10, 2016 by Grzegorz Juszczak 1 Comments , , , ,

Packstack Error: Command exceeded timeout
Pretty often after rebooting Controller node or powering it on after shutdown, the Horizon (OpenStack Dashboard) is not responding, but we know that it worked before reboot. This issue may be caused by httpd service (Apache), which entered failed state right after powering on the Controller node.

This results in browser’s connection problem to the Horizon:

chrome_unable to connect
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Cloud Computing

KVM OpenStack Error: /Stage[main]/Nova::Db::Sync/Exec[nova-db-sync]

Aug 7, 2016 by Grzegorz Juszczak 1 Comments , , , ,

Packstack Error: Command exceeded timeout
Few times during KVM based OpenStack (Mitaka, Newton) automated installations using packstack we encountered DB synchronization errors.

It turned out, that these installation errors appeared due to slow network and/or poor hardware performance of KVM virtualized hardware used to build OpenStack virtual nodes (Controller, Network, Compute).
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Linux

How to add user to sudoers – configure sudo access

Aug 5, 2016 by Grzegorz Juszczak 0 Comments , , , , , , , ,

configure sudo access in redhat
The sudo command offers a mechanism for providing trusted users with administrative access to a system without sharing the password of the root user.
A sudoer (regular user added to sudoers) once authenticated, can execute the administrative commands like they were run by the root user.

In this tutorial we present two examples:

  • How to add regular user to the wheel group and give the wheel group the unlimited root access
  • How to add particular user to the sudoers

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Linux

Yum – find out which RPM package provides particular file or command

Aug 3, 2016 by Grzegorz Juszczak 0 Comments , , , , , , ,

Yum – find out which RPM package provides particular file or command
Have you ever wondered how to find RPM package which contains particular script, application or command in your RedHat / CentOS or any other Yum / RPM based operating system? Have you ever needed to find the RPM package which provides some service or feature?

Yum package manager provides parameters to fast and easy search for particular files / features in Red Hat / CentOS RPM repositories:
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Linux

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

Jul 28, 2016 by Grzegorz Juszczak 0 Comments , , , , , , , , ,

enable disable configure kdump on centos redhat rhel
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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Linux

Setup Puppet Master and Multiple Agents on CentOS 7

Jul 19, 2016 by Grzegorz Juszczak 0 Comments , , , , , ,

install and configure puppet 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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Linux

Install Xfce 4 Desktop Environment on CentOS 7

Jul 1, 2016 by Grzegorz Juszczak 5 Comments , , , , , , ,

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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Linux, Virtualization

Install and Configure KVM (Bridge Net Interface) on CentOS 7 / RHEL 7

Jul 1, 2016 by Grzegorz Juszczak 29 Comments , , , , , , , ,

kvm installation configuration setup on centos7 redhat7
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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Linux

Install and Configure Elasticsearch Cluster on CentOS 7 nodes

Jun 18, 2016 by Grzegorz Juszczak 0 Comments , , , , , , , , , ,

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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