Thursday, November 28, 2013

How to disable network manager Red Hat 6 based distributions (RHEL, CentOS, Oracle Linux)

To stop Network Manger ( for example then using pacemaker cluster) execute as root:
service NetworkManager stop
To prevent Network Manager Service from starting at boot execute as root:
# chkconfig NetworkManager off

Keep in mind that you now need to manually configure your network interfaces.

Provided by:Forthscale systems, cloud experts

Wednesday, November 27, 2013

How to turn off SELINUX in Red - Hat based distributions including CentOS, Oracle Linux and Fedora?


To check  if SELinux is running execute following command:
# getenforce

To disable it, execute the following command:
# setenforce Permissive

This will put selinux in a passive (allow all) mode and last until the machine is rebooted.
 To permanently disable it, change SELINUX= line in: /etc/sysconfig/selinux.


Provided by:Forthscale systems, cloud experts

Saturday, November 09, 2013

working and tested USB install procedure for RH 6 based distributions (RHEL 6.x, CentOS 6.x, Oracle Linux 6.x and others)

We needed to install CentOS 6.4 machines with USB and got into absolute madness. All RHEL cones have no working procedure and workarounds consisted of using FAT32 partition with 3rd party tools (problematic with install ISO files greater than 4GB) or multiple partitions and remounts. Until we found a very simple solution that did not work as well and fixed it.

To create the USB You will need:
  • Red hat based distribution to create the USB (in our case CentOS-6.4-x86_64-bin-DVD1.iso)
  • Actual CD iso image 
  • Fedora livecd-iso-to-disk script
Steps are very simple:
Insert the USB stick to the port.
You need to find out the device name (for ex. /dev/sdb1 )
On systems with auto-mount just run df -h or plug it in and run dmesg | tail -20

Install livecd tools:
yum install livecd-tools

Make sure it is bootable  (for ex. /dev/sdb1, via editing it`s parent - sdb ):
/sbin/parted /dev/sdb
(parted) toggle 1 boot
(parted) quit

Format it with ext3 (does not support ext4)
mkfs.ext3 /dev/sdb1

Prepare the USB (for example using CentOS 6.4):
livecd-iso-to-disk --reset-mbr CentOS-6.4-x86_64-bin-DVD1.iso /dev/sdb1

Your USB is ready, it will boot but fail to install since it is missing install root, so we need to fix it.
Edit exlinux.conf, you will see something similar to:
append initrd=initrd.img stage2=hd:UUID=791fc126-638c-4f28-8837-f3c2eae31e57:/images/install.img repo=hd:UUID=791fc126-638c-4f28-8837-f3c2eae31e57:/

what is mising is directive "root=" so you need to switch the line to something similar to: 
append initrd=initrd.img root=UUID=2cd71b0d-09a0-47b6-97ef-02c3fa90e9d3 repo=hd:UUID=2cd71b0d-09a0-47b6-97ef-02c3fa90e9d3:/

save the file and boot fro USB. It will install your OS.

Provided by: Forthscale systems, cloud experts