Upgrading NIOS Software

Will see Upgrading NIOS Software in this post.

Before upgrading do the pre-implementation things for safer side mentioned below.

Check the current version of Infoblox execute below command in web console

admin> show version
Upgrading NIOS Software

Check the license using below command in web console

admin> show license

Note: If the NIOS holding temp license, it’s not advisable to upgrade the Version. It will lead to lose the GUI

Now we must take the Infoblox appliance database backup. Here we are mentioning NIOS configuration and discovery files as database. If anything goes wrong, we can use this backup to restore it to previous stat of the NIOS.

Grid -> Grid Manager -> Backup -> Manual Backup
-> My Computer -> Backup
  1. Download the upgrade binaries (Bin/ Bin2) file from Infoblox support portal and do remember the path where you saved the file


Step 1: 

Click on download tab and you will get next screen. From there select “NIOS Archives (.BIN/2 files)”

Upgrading NIOS Software

Step 2:  

             Once selected “NIOS Archives (.BIN/2 files)” from the dropdown list, next click on “Available for download” button

Upgrading NIOS Software

Step 3: 

      On next step you will get list of available download and from there click the appropriate version BIN or BIN2 file to download the upgrade. We can avoid “.DDI.OVA FILES” and “CHECKSUM FILES”, because it not required for the upgrade process.

Upgrading NIOS Software

Recommended to download the .BIN Files for the appropriate version.

Download and keep it in a host which in same network to upload in Grid Master GUI for upgrade and do remember the path.

Upgrading NIOS Software:

  1. Upload the binaries to Infoblox Grid Master (Grid -> Upgrade -> Upload)
  2. Once upload completed, Distribute button will be enabled. Then click on Distribute  to distribute the uploaded binaries to remote nodes (Grid -> Upgrade -> Distribute)
  3. Once distribution completed, Test button will be enabled. To verify the integrity of upgrade files click Test (Grid -> Upgrade -> Test)
  4. Finally click on upgrade to apply the update (Grid -> Upgrade -> Upgrade)

Post Upgrade of NIOS please do the below checks:

  • 1. Revert all nodes to the previous version (Grid -> Upgrade -> Revert -> Grid)

             Grid Master will display warning message. Read the warning carefully and then click Yes to proceed further.

  • In absence of Grid Master GUI, we can restore the backup to set NIOS Configuration to the previous stat.

Reference: Infoblox document

How to install RHEL 8

We are going to learn how to install RHEL 8 Operating system in this post. It supports “Appliction Stream” which will allow developer tools and read our previous post to know more about RHEL 8 features.

Minimum System Requirements:

  • 4 GB RAM
  • 20 GB unallocated disk space
  • 64-bit x86 or ARM System

and it will supports below architecture,

  • AMD or Intel x86 64-bit
  • 64-bit ARM
  • IBM Power Systems, Little Endian & IBM Z

Keep the RHEL 8 Media or Image file ready to start the installation. Use the below link to download RHEL 8


Boot the system using RHEL 8 media or image file and it will start the installation like below and by using “Tab” select “RedHat Enterprise Linux 8.0.0″and press “Enter” key in keyboard to start the installation.

How to install RHEL 8

On next screen, you will get a list that is asking you to select the System language and keyboard layout like below. Select your preferred language and click on continue

How to install RHEL 8

Then next you will get a screen which is the place to provide all information to install the operating system. Click on “Installation Destination” for partitioning.

How to install RHEL 8

In next screen, select “Automatic” for auto partitioning, which is done by Operating System itself. In this option i will take all the available disk for installation

Select “Custom” to do partitioning by yourself. Here you need to select the required mount points and size concern to that mounts. Default mount points will be /(root), swap, /boot. See the below screenshots of custom partitioning which i done in this installation.

How to install RHEL 8

Select the partition type “Standard Partition, LVM, LVM Thin Provisioning” which type you want to create partition. Here i selected LVM type for this installation. LVM is best option where you can extend or reduce the partition size whenever needed.

How to install RHEL 8

Select Filesystem(partition) and provide size of the filesystem like below

How to install RHEL 8

Finally i have created few of the filesystems using available disk space with LVM. Click on done from the top left side of the screen.

How to install RHEL 8

Next screen it will ask for the confirmation to make changes in disk. So, Click on “Accept Changes” to proceed further.

How to install RHEL 8

Next you can see a window where you can select the Language, Date and time, Time zone, network settings, Installation source, Installation Destination and Software selection.

Click on “software selection”

How to install RHEL 8

You will find a screen like below. From that you can select the option based on you Configuration, for what you are going to use this server. I used “Minimal Install”. Click on Done from the top left side corner of the screen and again click “Begin Installation”.

How to install RHEL 8

Now it will start the installation and the same time it will show you the option to set password for root user and if you want to create any other user, you can create and click “Done”

How to install RHEL 8
How to install RHEL 8

After the Installation click on “Reboot” from the bottom right side corner of the screen and finally system will boot up with new operating system installed and prompt for username and password.

How to install RHEL 8

Now your system is ready for production.

Thanks for reading this post.

Reference: RedHat Documentation

RedHat Enterprise Linux 8 (RHEL 8) released

RedHat Enterprise Linux 8 (RHEL 8) released

RedHat Enterprise Linux 8 (RHEL 8) released on 7th May 2019 and another important thing is that this happened after acquisition of RedHat by IBM on 28th October 2018.

Release Date:

RHEL 8 released on 7th May 2019 and now its available for production environment.

RHEL 8 Download link:

RedHat Enterprise Linux 8 (RHEL 8) released


AMD64, Intel 64-bit, 64-bit ARM, IBM Power Systems, and IBM Z 


RHEL 8 uses upstream Linux kernel 4.18

This is Secure, Stable and good foundation for hybrid cloud deployments.

New Features:

It Supports 4PB Physical memory

Wayland is default display server, instead of Xorg.

XFS supports shared copy-on-write data extends.

Now cockpit is default package and it comes along with RedHat OS image

RHEL 8 distributed with two main repositories: BaseOS & AppStream

RHEL 8 comes with new version of yum which is based on DNF.

nftables replaces iptables in network framework and we can convert existing iptables rules to nftables format for use.

Nginx 1.14 available in default repository.

Now in RHEL 8 sosreport can report any load of eBPF (extended Berkeley Packet Filtering) programs and maps

Geoliet2 database replaces geolite

In Cluster part we have new pcs commands to list and test available watchdog devices.

In the next post will see how to install RHEL 8

Reference: RedHat access portal

How to Register and Enable RedHat Subscriptions, Repositories for RHEL7

How to Register and Enable RedHat Subscriptions, Repositories for RHEL7

This post will guide you to know How to Register and Enable RedHat Subscriptions, Repositories for RHEL7 before system full upgrade or to install any packages from EPEL Repository in RedHat.

Enabling RedHat repositories are mandatory to install any packages using yum. RedHat subscription has the registered system details once the registration has been done.


All we need is newly installed system with RedHat 7.

Registering and Activating RedHat Subscrition:

As a first step we should go to the RedHat Customer portal and register there. After the successful registration do remember the credentials.

Now login to the RHEL7 server and use the below command to register your system to RedHat Customer portal with RedHat credentials which you created just before

#subscription-manager register --username <username> --password <password>

Once register your system, use the “list” option to get the all available subscription and than note down the subscription pool id which you need to activate it.

#subscription-manager list -available

if your not getting any list, than your system registration with RedHat customer portal is not purchased for subscription. Please get in touch with RedHat to proceed further.

Once you got the list of available subscription, you can use the below command to activate the subscription

#subscription-manager subscribe --pool=Pool ID number

To know the status of consumed subscription use the below command

#subscription-manager list –consumed

To list the available subscription use the below command

#subscription-manager list

Once your system registered with RedHat customer portal and activated subscription, you can enable the repositories . Use the below command to list the repositories for you subscription.

#subscription-manager repos --list

use the below command to list the available repository

#yum repolist all

To enable a specific repository, open “vi /etc/yum.repos.d/redhat.repo” file and ensure that “enbaled=1” for concern repository which you want to enable

Now list only enabled repository by executing below command

#yum repolist

Now you can use required yum commands to update your system/ install any packages like below

#yum update
#yum install <package_name>

Reference: RedHat portal

How to install Nagios Core server 4.4.3 on RHEL 6/7 & CentOS 6/7

This post will help you to know How to install Nagios Core server 4.4.3 on RHEL 6/7 & CentOS 6/7.

Nagios is a powerful monitoring tool. It will help to monitor a infrastructure.

It will monitor applications, service and entire infrastructure.

Required Packages:

  1. httpd
  2. php
  3. php-cli
  4. gcc
  5. unzip
  6. wget
  7. glibc
  8. glibc-common
  9. gd
  10. gd-devel
  11. net-snmp
[root@nagiosrv ~]yum install httpd php php-cli gcc unzip wget glibc glibc-common gd gd-devel net-snmp

As we have installed httpd and this will be useful when we access the Nagios core to manage through web console.

 [root@nagiosrv yumrepo]# systemctl start httpd 

Now create Nagios user account using below command:

[root@nagiosrv yumrepo]# useradd Nagios
[root@nagiosrv yumrepo]# passwd nagios
Changing password for user nagios.
New password:
BAD PASSWORD: The password contains the user name in some form
Retype new password:
passwd: all authentication tokens updated successfully.

Now we need to create a group “nagcmd” to setup Nagios and then add the users “nagios” & “apache”   to be a part of group: nagcmd

[root@nagiosrv yumrepo]# groupadd nagcmd
[root@nagiosrv yumrepo]# usermod -a -G nagcmd nagios
[root@nagiosrv yumrepo]# usermod -a -G nagcmd apache

Ñow its time to start Nagios Core server installation

Since Nagios third party tool, we need to download first for installation using below commands:

[root@nagiosrv ~]# cd /opt
[root@nagiosrv opt]# wget https://assets.nagios.com/downloads/nagioscore/releases/nagios-4.4.3.tar.gz
[root@nagiosrv opt]# tar -xvf nagios-4.4.3.tar.gz
[root@nagiosrv nagios-4.4.3]# ./configure --with-command-group=nagcmd
[root@nagiosrv nagios-4.4.3]# make all
[root@nagiosrv nagios-4.4.3]# make install
[root@nagiosrv nagios-4.4.3]# make install-init
[root@nagiosrv nagios-4.4.3]# make install-daemoninit
[root@nagiosrv nagios-4.4.3]# make install-commandmode
[root@nagiosrv nagios-4.4.3]# make install-config
[root@nagiosrv nagios-4.4.3]# make install-exfoliation

Now configure Apache for Nagios installation using below command:

[root@nagiosrv nagios-4.4.3]# make install-webconf

Will configure Apache authentication for nagiosadmin which is default user. Don’t change this username. If you are changing then need to do more changes in configuration file.

[root@nagiosrv nagios-4.4.3]# htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin

Now restart the apache

[root@nagiosrv nagios-4.4.3]# systemctl restart httpd

As a next step need to install Nagios plugins, once installed Nagios core using below commands:

[root@nagiosrv nagios-4.4.3]# cd /opt
[root@nagiosrv opt]# wget http://nagios-plugins.org/download/nagios-plugins-2.2.1.tar.gz
[root@nagiosrv opt]# tar -xvf nagios-plugins-2.2.1.tar.gz
[root@nagiosrv opt]# cd nagios-plugins-2.2.1

Now install and compile the plugins using below command:

[root@nagiosrv nagios-plugins-2.2.1]# ./configure --with-nagios-user=nagios --with-nagios-group=Nagios
[root@nagiosrv nagios-plugins-2.2.1]# make
[root@nagiosrv nagios-plugins-2.2.1]# make install

We installed Nagios core and plugins. So, now will check and verify the configuration using below command:

[root@nagiosrv nagios-plugins-2.2.1]#
/usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg

The output should give 0 Errors and 0 Warnings. If you get the same, then will start the Nagios like below

[root@nagiosrv nagios-plugins-2.2.1]# systemctl start

Check SELinux mode using below command:

[root@nagiosrv ~]getenforce

If SELinux is in Enforcing mode, Than change it to Permissive mode or disable it like below

[root@nagiosrv ~]# setenforce 0

Now make sure to enable web server permanently in firewall using below command:

[root@nagiosrv ~]# firewall-cmd --permanent

Execute below command to make affect in firewall changes which we did using our previous command

[root@nagiosrv ~]# firewall-cmd –reload

Finally we have done everything and now will check whether the web console working on not

Enter url like below in your web browser and replace the IP_ADDR with your server ip


It will ask for the username and password. Remember that we already created a user name “nagiosadmin”. We can use that to login the console.

How to install Nagios Core server 4.4.3 on RHEL 6/7 & CentOS 6/7

Enter the nagiosadmin credentials and the web console looks like below

How to install Nagios Core server 4.4.3 on RHEL 6/7 & CentOS 6/7

From the left side pan click on “Hosts” and it will show list of hosts which is added for monitoring.
Since, we doesn’t added any host, it will show only localhost, which is Nagios server like below

How to install Nagios Core server 4.4.3 on RHEL 6/7 & CentOS 6/7

Finally we installed and configured Nagios server. Thanks for readin

VMware:Events:warning: Event: com.vmware.vc.HA.NotAllHostAddrsPingable

We are going to see how to resolve VMware:Events:warning: Event: com.vmware.vc.HA.NotAllHostAddrsPingable or management host not responding in cluster issue in VMWare VCentre

VMware:Events:warning: Event: com.vmware.vc.HA.NotAllHostAddrsPingable


  1. Login to VMWare webclient and check the status of the host
  2. If the host is non responsive mode, try to ping host by using IP Address of the host.
  3. If the ping request getting failed, then try to login to the IDrac for the host status
  4. Try to login the host through virtual console
  5. if the server is not responding , reboot the server and be informed to the concern team before rebooting or if its responding and asking for password, simply restart the ESXi and check the server status again vcenter.
  6. same time check nslookup and hostname commands are giving appropriate output.

Above steps mostly will help to resolve this issue.

what is split brain syndrome in clusters?

In this post we are going to see what is split brain syndrome in clusters?

Split brain syndrome is a state on a cluster where each cluster nodes are divided into small clusters and each one will believe themselves as itself only an active cluster.

Each nodes believes that all other nodes are dead and simultaneously will try to access the same data/ disks, which can be lead to data corruption. This situation will occur during the cluster reformation.

When one or more nodes fails, the cluster itself will reform the cluster with the available nodes.

Note: High Availability clusters will use some mechanism like CMAN, Pacemaker, HP ServiceGaurd, and Linux HA to avoid split brain syndrome.

Common methods to address split brain syndrome:

  1. I/O Fencing
  2. Quorum/ Local Disk
  3. Quorum Server
  4. Tie – Breakers
  5. STONITH(Shoot The Other Node In The Head)

How to boot with an old kernel in RHEL4,5,6/CentOS

In this post, we are going to see How to boot with an old kernel in RHEL4,5,6/CentOS Operating systems.

How to boot with an old kernel in RHEL4,5,6/CentOS

RedHat Operating System uses GRUB boot loader as default one globally.

We can boot update the kernel using Yum/ RPM Package management like other package upgrades which we are doing.

Use the below command to know which boot loader installed on your OS.

#grubby -bootloader-probe

Changing kernel:

/boot/grub/grub.conf is the grub configuration file.

#cat /boot/grub/grub.conf 

default=0 timeout=5 password --encrypted $6$GXGrYVEnbKXAnQoT$p64OkyclNDt4qM2q47GMsgNxJxQaclNs79gvYYsl4h07ReDtJpt5P5kQn1KQ52u2eW8pKHTqcG50ffv0UlRcW0 splashimage=(hd0,0)/grub/splash.xpm.gz hiddenmenu title Red Hat Enterprise Linux 6.4 (2.6.32-358.el6.x86_64) ===> kernel 0 root (hd0,0) kernel /vmlinuz-2.6.32-358.el6.x86_64 ro root=/dev/mapper/vg_geeklab-lv_root rd_NO_LUKS KEYBOARDTYPE=pc KEYTABLE=us LANG=en_US.UTF-8 rd_NO_MD SYSFONT=latarcyrheb-sun16 crashkernel=auto rd_LVM_LV=vg_geeklab/lv_swap rd_LVM_LV=vg_geeklab/lv_root rd_NO_DM rhgb quiet initrd /initramfs-2.6.32-358.el6.x86_64.img title Red Hat Enterprise Linux 6.3 (2.6.32-279.el6.x86_64) ===> kernel 1 root (hd0,0) kernel /vmlinuz-2.6.32-279.el6.x86_64 ro root=/dev/mapper/vg_geeklab-lv_root rd_NO_LUKS KEYBOARDTYPE=pc KEYTABLE=us LANG=en_US.UTF-8 rd_NO_MD SYSFONT=latarcyrheb-sun16 crashkernel=auto rd_LVM_LV=vg_geeklab/lv_swap rd_LVM_LV=vg_geeklab/lv_root rd_NO_DM rhgb quiet initrd /initramfs-2.6.32-279.el6.x86_64.img

In this, we can see Default will be 0. From this, we can understand OS will read by the default top kernel.

Whenever we are upgrading the kernel that will be coming up and considered as 0 and old kernel will be marked as 1.

So, We should change the number from “0” to “1” on below line of /boot/grub/grub.conf file using vi editor and save it.


We done the needed configuration change to boot the OS with an old kernel.

On the next boot it will take effect.

Using below command reboot the system and then check whether its booting with old kernel or new one.

#shutdown -r now

Use the below command to check the kernel versions which is in use right now

#uname -r

awk command in linux

awk command in linux

We are going to see how to use awk command in Linux in this post.

It’s a scripting language and it’s used to generate Reports and Data Manipulation.


#awk <option> 'criteria {action}' input_file > output_file

Awk command to print file content:

[root@localhost ~]# awk '{print}' testfile.txt
Abu 1234
Thahir 5678
Tharun 9101
Rishi 2345

Above example is only to print all the content of a file.

Awk command to print the lines which match with the given pattern:

[root@localhost ~]# awk '/Rishi/{print}' testfile.txt
Rishi 2345

awk command to split a line to fields:

$1 will be considered the first word as the first field in a line. accordingly $2,$3, etc…

[root@localhost ~]# awk '{print $2}' testfile.txt
[root@localhost ~]#

Built-in variables in awk:

NF:     We can print the last field of the lines by using NF in awk command


[root@localhost ~]# awk '{print $NF}' testfile.txt

NR:     Using NR built-in option, we can print the specific fields along with line numbers and can print all content of a file along with the line numbers. Also, we can print the range of lines using NR in awk command.


1. Displaying specific row with a specific field in a file

[root@localhost ~]# awk 'NR==2 {print $1,$3}' testfile.txt
Thahir 30000

2.Displaying content of a range of lines(from 2 to 4th line)

[root@localhost ~]# awk 'NR==2, NR==4 {print $1,$3}' testfile.txt
Thahir 30000
Tharun 20000
Rishi 15000


Thanks for reading our blog. Please drop your comments.

How to install Ansible on RHEL7/ CentOS7

We are going to see how to install Ansible on RHEL7/ CentOS7 in this post.

Control node needs to install Python 2.6 or latest version and windows doesn’t support for control node.

Since the ansible agentless tool, on Managed hosts no need to install any specific agent/client. And need to install python 2.4 or latest version on managed hosts.

How to install Ansible on RHEL7/ CentOS7

Installing Ansible on RHEL7/ CentOS7:

To install the Ansible we should have Enabled EPEL repository on our server already

Once enable EPEL Repo, then we can start installing Ansible using yum.

[root@localhost ~]# yum install ansible -y

Post installation of ansible will check the version of Ansible by using below command

[root@localhost ~]# ansible --version
ansible 2.7.9
 config file = /etc/ansible/ansible.cfg
 configured module search path = [u'/root/.ansible/plugins/modules', u'/usr/share/ansible/plugins/modules']
 ansible python module location = /usr/lib/python2.7/site-packages/ansible
 executable location = /usr/bin/ansible
 python version = 2.7.5 (default, Aug 2 2016, 04:20:16) [GCC 4.8.5 20150623 (Red Hat 4.8.5-4)]
[root@localhost ~]#

Finally, we installed ansible over our machine which we are going to take it as a control node.

Hereafter if we want to deploy or manage any remote hosts(Managed Host) from the control node, SSH authentication is mandatory. So, We should copy and paste the SSH keys to the remote hosts to make the communication available between the control and managed node.


Reference: Ansible documented site