This is required when there is no RAID controller card available for the server and the only solution is software RAID. This post makes changes to partitions, so if there is any existing data on any disks being used for this purpose, it should be backed up prior to creating the RAID array as per standard best practices. 1. In order to mirror the disk, information about partition has to be obtained. This can be done with one of the following commands: # parted /dev/sda u s p # fdisk -l … [Read more...] about How to Mirror Swap, Boot and Root Partions in CentOS/RHEL 7 Using mdadm Utility
Linux
MySQL Server Error – “Can’t Create A New Thread (errno 11)”
OS error 11 is "Resource temporarily unavailable". The most common cause of receiving this error when trying to create a new thread is having hit the process's kernel enforced a limit on open file descriptors. The second most common cause is having hit the process's kernel enforced limit on the number of processes/threads. Here are the factors involved: The system-wide limits: sysctl -e fs.file-max && sysctl -e kernel.threads-max The per-process limits (in a *new* shell): ulimit -n, grep … [Read more...] about MySQL Server Error – “Can’t Create A New Thread (errno 11)”
SLES 12: Database Startup Error with ORA-27300 ORA-27301 ORA-27303 While Starting using Srvctl
The Problem 12.1 RAC database error while starting via srvctl, alert log showing database startup and further goes down: alert_ORCL2.log inside [oracle base]/diag/rdbms/[db name]/[SID name]/trace: Fri Nov 03 15:06:25 2017 Adjusting the default value of parameter parallel_max_servers from 960 to 486 due to the value of parameter processes (600) Starting ORACLE instance (normal) (OS id: 19684) . . Fri Nov 03 15:10:45 2017 Process startup failed, error stack: Fri Nov 03 15:10:45 … [Read more...] about SLES 12: Database Startup Error with ORA-27300 ORA-27301 ORA-27303 While Starting using Srvctl
How to Verify a Lun is in Active/Optimized Mode when ALUA Is Configured on Storage
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
How to Create Yum Repository For System Packages Installation in CentOS/RHEL
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
Getting “parsing errors” When Running ‘yum repolist’
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’
How to Install Apache, MariaDB, and PHP (FAMP) stack on FreeBSD 11
In this tutorial we will show you how to install Apache, MariaDB, and PHP on FreeBSD 11. If you don't know FAMP is the acronym of FreeBSD, Apache, MySQL/MariaDB, PHP. FreeBSD 11 is the latest version right now when this article was made. Prerequisites Before you begin with this guide, you should at least have basic knowledge of linux or unix, know basic shell command for linux or unix, have login as root user and of course you need FreeBSD 11 installed on your PC or server. Step 1 – … [Read more...] about How to Install Apache, MariaDB, and PHP (FAMP) stack on FreeBSD 11
How to configure apache virtual host on ubuntu
In this tutorial, we will guide you to configure the apache virtual host or vhost on ubuntu 16.04. Using virtual host allow the administrator to use one server to host multiple domains or sites off of a single interface or IP by using a matching mechanism. Basically, you can you one IP address to server multiple domain names. Virtual host method is widely used in a shared hosting provider. Prerequisites Before you begin with this guide, you should at least have basic knowledge of linux, know … [Read more...] about How to configure apache virtual host on ubuntu
How to Clone Linux disk partition over network using dd
In this tutorial, we will show you how to clone Linux harddisk partition over a network, in this tutorial we will use dd command. For the guys who don’t know what dd is - it is a command-line utility for Unix and Unix-like operating systems whose primary purpose is to convert and copy files. Clone Linux harddisk has advantages because we don’t need to reinstall and configure again the applications especially in Linux that we used as a server. Prerequisites This article assumes you have at … [Read more...] about How to Clone Linux disk partition over network using dd
How to Change Timezone from CST To EST in CentOS/RHEL 7 Server
Question: How to change timezone in CentOS/RHEL 7 server from EST to CST. Follow the below steps to change the timezone to CST. (Execute the below commands as root user) 1. List all the available timezones using the below command: # timedatectl list-timezones 2. Locate the correct timezone you need that is in the central timezone. 3. Set the specific timezone. For example, to set central timezone: # timedatectl set-timezone America/Chicago 4. Run the "date" command to verify the … [Read more...] about How to Change Timezone from CST To EST in CentOS/RHEL 7 Server