This document describes steps to troubleshoot kubectl error: The connection to the server x.x.x.x:6443 was refused – did you specify the right host or port? 1. The kubectl should be executed on the Master Node. 2. Current user must have Kubernetes cluster configuration environment variable (Details of how to are listed under section Preparing to […]
Archives for June 2019
“uname” Command Examples to Check UNIX/Linux Version
The uname command displays system information. Apart from the hostname command, you can also use the “uname -n” command to display the host name of your system. Without any flags, the uname command will display the operating system that your are using. Here are some useful options: Option Description -a Displays all information -s Displays […]
How to run Hadoop without using SSH
The start-all.sh and stop-all.sh scripts in the hadoop/bin directory will use SSH to launch some of the Hadoop daemons. If for some reason SSH is not available on the server, please follow the steps below to run Hadoop without using SSH. The goal is to modify all “hadoop-daemons.sh” with “hadoop-daemon.sh“. The “hadoop-daemons.sh” simply runs “hadoop-daemon.sh” […]
How To Modify Hadoop Log Level
By default, Hadoop’s log level is set to INFO. This can be too much for most instances, as it will generate huge log files, even in an environment with low to moderate traffic. Changing the root logger in log4j.properties file in Hadoop will not change the log level. Follow the steps below for changing the […]
Why Does a Lun World Wide ID Starts with the Number 3 in Linux dm-multipath
Question: Why Does a Lun World Wide ID Starts with the Number 3? When mapping a lun to the server with wwid -> 640xxxxxxxxxxxxxxxxxxxxxx, but from the `multipath -ll`, all wwid begin with 3 like 3640xxxxxxxxxxxxxxxxxxxxxx. # multipath -ll 3640xxxxxxxxxxxxxxxxxxxxxx dm-27 HUAWEI,XSG1 size=400G features=’1 queue_if_no_path’ hwhandler=’0′ wp=rw `-+- policy=’round-robin 0′ prio=1 status=active |- 14:0:0:28 sdbg […]
How to enable md5 Hashing in Linux
Question: How to make sure that all passwords (root and non-root) are stored as MD5 Hashing standard? NOTE: Here we are assuming that the default Hashing protocol is non MD5. Please follow the below steps in order to achieve the same: 1. Run the below command: # cat /etc/pam.d/system-auth | egrep “password|sufficient” Output would be […]
How to Install and Configure Kerberos in CentOS/RHEL 7
Confguration of Kerberos V5 1. Install krb5-libs, krb5-server, and krb5-workstation packages 2. Edit the /etc/krb5.conf and /var/kerberos/krb5kdc/kdc.conf to reflect your realm name and domain to realm mappings. A simple realm can be constructed by replacing instances of EXAMPLE.COM and example.com with your domain name (making sure you keep the same case), and by changing kerberos.example.com […]
–force V/s –nodeps : rpm command options to install or uninstall a package
These rpm options can potentially corrupt a Linux server so severely a reinstall may become necessary. So be cautious while playing with them. –force V/s –nodeps –force Ignore package and file conflicts for install — package might stop working properly leading to serious issues –nodeps Do not check dependencies — package might not work properly […]
Linux “rm” Command Examples
Unix includes two commands that you can use to delete files and directories: rm (remove) and rmdir (remove directory). You can also use “rm” command to remove a directory as well. In this post, we are going to discuss on rm command in Linux. rm is a Linux terminal command used to delete/remove files & […]
How to Create and Query a BTRFS File System
The Basics The btrfs file system is designed to meet the expanding scalability requirements of large storage subsystems. As the btrfs file system uses B-trees in its implementation, its name derives from the name of those data structures, although it is not a true acronym. A B-tree is a tree-like data structure that enables file […]