Introduction This article shows a test in which a whole Red Hat Enterprise Linux system is backed-up to another disk partition, the files system is then destroyed using fdisk (to simulate a disk failure), and finally, the system is restored successfully. All the steps can be used for CentOS/RHEL 4,5,6,7. NOTE 1: Since there are different kinds of storage, we could not make detailed test on them, and also consider that any mistake will destroy the system and difficult to recover, so we … [Read more...] about How to Backup and Restore a Whole CentOS/RHEL/Fedora system with the dump/restore commands?
CentOS / RHEL 4
The tables below list the major and minor Red Hat Enterprise Linux updates, their release dates, and the kernel versions that shipped with them. Red Hat does not generally disclose future release schedules. To find your Red Hat Enterprise Linux release please: $ cat /etc/redhat-release For Example: $ cat /etc/redhat-release Red Hat Enterprise Linux Server release 6.6 (Santiago) To find your kernel version please: $ uname -a For Example: $ uname -a Linux geeklab … [Read more...] about Red Hat Enterprise Linux Release Dates
What is OOM Killer? The OOM killer, a feature enabled by default, is a self-protection mechanism employed the Linux kernel when under severe memory pressure. If the kernel can not find memory to allocate when it's needed, it puts in-use user data pages on the swap-out queue, to be swapped out. If the Virtual Memory (VM) cannot allocate memory and can't swap out in-use memory, the Out-of-memory killer may begin killing current userspace processes. it will sacrifice one or more processes in … [Read more...] about How to disable the Out of memory or oom-killer in CentOS/RHEL 4
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
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
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
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)