Grub2 recovery

centos / cPanel server grub2 recovery steps : 

1. Boot your server from a live CD 
2. type fdisk -l command to find out your primary disk partition where you want to recover your grub. 

3. mkdir /media/sda1
4.  mount /dev/sda1 /media/sda1 
5.  mount --bind /dev /media/sda1/dev
6.  mount --bind /proc /media/sda1/proc 
7.  chroot /media/sda1
8.  grub-install /dev/sda
9.  If you get an error, then we need to execute this command -> grub-install --recheck /dev/sda 

10 After the grub installation we will exist from chroot => exit

11 umount /media/sda1/proc
12 umount /media/sda1/dev
13 umount /media/sda1 
14 reboot the server

CSF WHM Internal Server Error

When trying to access CSF via WHM it's coming back with:

Internal Server Error

500
No response from subprocess (/usr/local/cpanel/whostmgr/docroot/cgi/addon_csf.cgi): subprocess exited with status 2

=================
We can check the error log here tail -f /usr/local/cpanel/logs/error_log while accessing csf through your WHM.

From the error log we can see which perl module is missing for csf. We can install the missing perl module using the follows command.

/usr/sbin/csf -x
/scripts/perlinstaller --force Net::LibIDN
/usr/sbin/csf -e
/usr/sbin/csf -u

But this is not fixed my 500 internal server error. I have fixed this issue by executing the following command.

curl -s configserver.com/free/csupdate | perl

Upgrade Firefox version to 21

I have upgraded my Fedora 16 firefox to the latest version 21. Please check my upgrade steps for this process.

[root@localhost ajeesh]# cd /usr/local/src/
[root@localhost src]# wget http://rpms.famillecollet.com/remi-release-16.rpm

[root@localhost src]# rpm -Uvh remi-release-16.rpm
warning: remi-release-16.rpm: Header V3 DSA/SHA1 Signature, key ID 00f97f56: NOKEY
Preparing...                ########################################### [100%]
   1:remi-release           ########################################### [100%]

[root@localhost src]# yum --enablerepo=remi list firefox
Installed Packages

firefox.i686                                                                  18.0-1.fc16                                                                       @updates

Available Packages                                                                                                                                                       
firefox.i686                                                                  21.0-4.fc16.remi                                                                  remi 

[root@localhost src]# yum --enablerepo=remi update firefox

Dependencies Resolved

========================================================================================================================================================================
 Package                                     Arch                              Version                                          Repository                         Size
========================================================================================================================================================================
Updating:
 firefox                                     i686                              21.0-4.fc16.remi                                 remi                               26 M
Installing for dependencies:
 xulrunner-last                              i686                              21.0-2.fc16.remi                                 remi                               19 M

Transaction Summary
========================================================================================================================================================================
Install       1 Package
Upgrade       1 Package

Total download size: 45 M
Is this ok [y/N]: y

Centos 6 32bit PAE kernel

There is no centos 6 32 bit PAE kernel. So you should be very careful while selecting a 32 centos6 OS on your server. Latter you can not upgrade more than 4GB RAM on your server. In the case of RAM upgrade you need a server migration from 32 bit CentOS 6 to 64 bit CentOS 6