CentOS/RHEL 6

This post briefly outlines how it possible to re-create the yum cache, or said in another way, force a fetch of the cache data from the enabled yum repositories. The enabled yum repositories are the ones in the following file /etc/yum.conf or in the following folder /etc/yum.repos.d that have their "enabled" setting to "1", e.g. : [public_ol6_latest] name=Oracle Linux $releasever Latest … [Read more...] about How to Re-Create the Yum Cache and/or Force a Fetch of the Package List of the Enabled Repositories

If the Linux server has device-mapper-multipath configured, you can run 'multipath -ll' to list how disks are grouped together. For ALUA mode, you can check if a disk is in the Active/Optimized or non-optimized group. This post, however, is to discuss how to use sg_rtpg command to check the target port group asymmetric access state (aas). Along with sg_inq command, you can check if a specific disk (/dev/sdX) is in Active/optimized group or not. You can use sg_rtpg to decode the status code … [Read more...] about How to Verify a Lun is in Active/Optimized Mode when ALUA Is Configured on Storage

A yum repository holds the rpms and metadata about the rpms. A yum repository must be configured in order to use yum on any yum based Linux system. This post provides steps to configure a yum repository for installing packages on CentOS/RHEL systems. Configuring yum repository server 1. Create a directory for you local repository, e.g. /home/mypackage_dir/repository. Move the RPMs into that directory. # cp /media/packages/* /home/mypackage_dir/repo 2. Fix some ownership and filesystem … [Read more...] about How to Create Yum Repository For System Packages Installation in CentOS/RHEL

The Problem When adding an extra repository of the public yum into existing yum repository configuration file, the following errors are shown: # yum repolist Loaded plugins: langpacks, ulninfo File contains parsing errors: file:///etc/yum.repos.d/public-yum-ol7.repo [line 91]: name=Latest Unbreakable Enterprise Kernel Release 4 for Oracle Linux 7Server (x86_64) [line 92]: baseurl=https://yum.oracle.com/repo/OracleLinux/OL7/UEKR4/x86_64/ [line 93]: … [Read more...] about Getting “parsing errors” When Running ‘yum repolist’

The Problem While starting lxc it gives the below error: lxc-start 1491315722.354 ERROR lxc_cgfs - Device or resource busy - failed to set memory.use_hierarchy to 1; continuing lxc-start 1491315722.354 ERROR lxc_cgfs - Device or resource busy - failed to set memory.use_hierarchy to 1; continuing lxc-start 1497957841.930 ERROR lxc_cgfs - Device or resource busy - failed to set memory.use_hierarchy to 1; continuing lxc-start 1497957841.937 ERROR lxc_cgfs - Device or resource busy - failed to … [Read more...] about ‘lxc_cgfs – Device or resource busy – failed to set memory.use_hierarchy to 1; continuing’ – error while starting LXC container

The Problem While changing password using the passwd command, the following error appears: "passwd: Module is unknown" The Solution There is a unknown PAM module pam_pwquality.so in /etc/pam.d/system-auth file. The pam_pwquality.so module should be used in CentOS/RHEL 7 rather than CentOS/RHEL 6. # cat /etc/pam.d/system-auth # This file is auto-generated. # User changes will be destroyed the next time authconfig is run. auth required pam_env.so auth sufficient pam_unix.so nullok … [Read more...] about “passwd: Module is unknown” – error while changing the password in CentOS/RHEL 6

Question: How to change the password hashing algorithm on a CentOS/RHEL system. 1. Check to current hashing algorithm : # authconfig --test| grep hash password hashing algorithm is sha512 2. Change default password hashing algorithm : # authconfig --passalgo=md5 --update or # authconfig --passalgo=sha5 --update Note : The new algorithm in passwd/shadow files will apply until next execution of passwd command. … [Read more...] about How to Switch Password Algorithm on CentOS/RHEL