CentOS/RHEL 8

The Problem All the dnf commands fail with the following error: # dnf repolist Oracle Linux 8 BaseOS Latest (x86_64) 0.0 B/s | 0 B 00:00 Failed to download metadata for repo 'ol8_baseos_latest' Error: Failed to download metadata for repo 'ol8_baseos_latest dnf was not able to refresh the cache as it could not reach the yum server itself, Hence pointing to cache being expired. # yum clean metadata Cache was expired … [Read more...] about Failed to Download Metadata for Repo ‘repo_name’

This post will help to change the network interface name using prefixdevname utility in CentOS/RHEL 8 systems. Installation and configuration 1. Install the required package using dnf utility: # dnf install prefixdevname 2. Append the net.ifnames.prefix=[ABCD] using grubby command: (ABCD to replaced with own prefix, eg: net). # grubby --update-kernel=$(grubby --default-kernel) --args="net.ifnames.prefix=net" 3. Reboot the system to take effect: # reboot 4. After system rebooted, … [Read more...] about How to change the interface name in CentOS/RHEL 8 using prefixdevname

Although NetworkManager is the default tool for configuring and managing the network services on CentOS/RHEL 8, there are situations where it may be necessary to permanently disable NetworkManager, and use alternative methods to configure and manage the network. This document describes how to permanently disable NetworkManager on CentOS/RHEL 8. Note: Use of "networks-scripts" is deprecated in CentOS/RHEL 8. Disabling NetworkManager in CentOS/RHEL 8 1. The following three commands are … [Read more...] about How to Disable NetworkManager in CentOS/RHEL 8

The Problem While executing the command "lsb_release -r" to display the release number of the currently installed distribution, user gets below error: # lsb_release -v -bash: lsb_release: command not found How this can be resolved? The Solution To check the RedHat/CentOS version one can use the “lsb_release” command. In most cases, the package providing this command is not installed by default on the systems. To check which package provides the lsb_release command use the below … [Read more...] about “lsb_release: command not found” – Fix in CentOS/RHEL

Virtual Data Optimizer (VDO) is a block virtualization technology that allows you to easily create compressed and deduplicated pools of block storage. This post outlines steps to create Virtual Data Optimizer(VD0) filesystem in CentOS/RHEL 8 systems. 1. Install VDO using dnf or yum. # dnf install install vdo Verify the package installation: # rpm -qa | grep vdo kmod-kvdo-6.2.0.293-50.0.1.el8.x86_64 vdo-6.2.0.298-10.el8_0.x86_64 2. Create a VDO disk: # lsblk | grep sdc NAME MAJ:MIN … [Read more...] about How To Create Virtual Data Optimizer(VD0) in CentOS/RHEL 7 and 8

"stratis" is the new volume manager introduced in the CentOS/RHEL 8 release. This post outlines steps to create or remove a new stratis filesystem in CentOS/RHEL 8 system. We will also see how to mount and umount a stratis filesystem in this post. Creating and mounting a stratis filesystem 1. Install Stratis packages: # rpm -qa | grep "strati*" stratisd-1.0.3-1.el8.x86_64 stratis-cli-1.0.2-1.el8.noarch 2. Enable and start the stratisd service: # systemctl enable --now stratisd # … [Read more...] about How To Create/Remove and Mount a Stratis Filesystem in CentOS/RHEL 8

What is early kdump support? In previous versions of CentOS/RHEL (5/6/7), the kdump service would start very late in the boot sequence. So early crashes information is lost during the booting. Starting CentOS/RHEL 8, a new kdump mechanism called "early kdump support" was introduced to tackle this issue. Early Kdump stores the vmlinuz and initramfs of the crash kernel inside the initramfs of the booting kernel and load them directly into the reserved memory (crashkernel) during early boot … [Read more...] about How to Configure Early-kdump Support Feature in CentOS/RHEL 8

This article explains how to bootup CentOS/RHEL 7 and 8 system into rescue mode or emergency mode. In CentOS/RHEL 7 and 8, both rescue mode and emergency mode are systemd targets which replaced the concept of runlevels in previous CentOS/RHEL versions. Rescue mode is equivalent to single user mode and requires the root password. Rescue mode allows you to repair your system in situations when it is unable to complete a regular booting process. Rescue mode will try to mount all local file … [Read more...] about How to Boot into Rescue Mode or Emergency Mode Through Systemd in CentOS/RHEL 7 and 8

In CentOS/RHEL 8 the network services scripts are not presented anymore(systemctl start network.service or /etc/init.d/network script). In order to restart the network services follow one of these two options. Using Network Manager Use the systemctl command to restart the NetworkManager service/target as shown below: # systemctl restart NetworkManager Using nmcli Tool Note: Run these commands from the GUI or the console, as the network will disable. # nmcli networking off # nmcli … [Read more...] about How to Restart Network Services in CentOS/RHEL 8