The Problem Messages such as the following are reported when running commands such as partprobe on a CentOS/RHEL system using LVM (Logical Volume Manager) and multipathing e.g. device-mapper-multipath or EMC PowerPath, etc.: Error: Error informing the kernel about modifications to partition /dev/sda1 -- Device or resource busy. This means Linux won't know about any changes you made to /dev/sda1 until you reboot -- so you shouldn't mount it or use it in any way before … [Read more...] about ‘Found duplicate PV’ warnings when using LVM with multipath storage in RHEL/CentOS
CentOS/RHEL 4
How to Automate Startup/Shutdown of Oracle Database and Listener on Linux
In many environments, it's desirable to have the Oracle database and listener automatically shutdown and startup when the server reboots. If you have that requirement, then follow the next several steps to automate your database and listener shutdown and startup: Steps to configure auto startup/shutdown 1. Edit the /etc/oratab file, and place a Y at the end of the entry for the databases you want to automatically restart when the system reboots. You might need root privileges to edit the … [Read more...] about How to Automate Startup/Shutdown of Oracle Database and Listener on Linux
How to Change Default Permission of /var/log/messages in CentOS/RHEL
By default, /var/log/messages* are created with read-write permissions for 'root' user only. There might be a requirement to make the log files world readable for eg to allow an application to read and process the data in it. Changing the permissions on such files using 'chmod' might be a temporary solution as they will be recreated with the original permission during the next logrotate cron job. This post will help understand how to set custom permissions (eg 644) on /var/log/messages … [Read more...] about How to Change Default Permission of /var/log/messages in CentOS/RHEL
How to Disable “alt+ctrl+Del” Key Combination causing reboot in CentOS/RHEL 4,5
The key combination “Ctrl+Alt+Del”, when pressed on a virtual console (black-screen tty), causes the system to reboot. This is the default behavior and sometimes people don’t like this feature as it may cause accidental reboots of the system. The post provides the procedure on how to disable “alt+ctrl+del” key combination in order to prevent an accidental shutdown. In case of CentOS CentOS/RHEL 4,5 the shutdown command is controlled by /sbin/init, described in /etc/inittab as: # Trap … [Read more...] about How to Disable “alt+ctrl+Del” Key Combination causing reboot in CentOS/RHEL 4,5
CentOS / RHEL : How to add new swap partition
Question I have a new disk attached to the system. How can I create a new swap partition using this disk on the system? Solution For the purpose of this post, let's assume that you do not have any swap configured on your system. /dev/sdc is the drive referenced with no partitions. Since we are going to make a single partition filling the disk, note that any data currently on that disk will be lost. Follow the steps given below to add /dev/sdc1 partition as the new swap partition on the … [Read more...] about CentOS / RHEL : How to add new swap partition
CentOS / RHEL 4 : How to configure interface bonding (NIC teaming)
Follow the 4 steps below to configure the bonding interface: 1. configure bonding driver, as well as the bonding mode and parameters using the configuration file /etc/modprobe.conf. # grep bond0 /etc/modprobe.conf alias bond0 bonding options bond0 mode=1 miimon=100 2. configure the save interfaces of the bond using the respective network scripts. # cat /etc/sysconfig/network-scripts/ifcfg-eth1 DEVICE=eth1 BOOTPROTO=none ONBOOT=yes MASTER=bond0 SLAVE=yes # cat … [Read more...] about CentOS / RHEL 4 : How to configure interface bonding (NIC teaming)