Fix datastore error “HostDatastoreSystem.Query VmfsDatastore CreateOptions” in ESXi

At home Lab I came across this error while adding a previously used Windows disk to ESXi. It appears half way while adding the disk via “Add Storage Wizard”. The error can be resolved by formatting the disk in DOS format using Parted utility inbuilt into Esxi. You need to SSH into the Esxi hosts for fixing.


Secure /etc/fstab in Linux

Its best to secure /etc/fstab as it contains all the mount locations and can lead to boot issues if any novice person tinkers/plays around with it. The secure mode can only be enabled /disabled by root user only and completely secure. There is a simple one line command for that as given.


Add and Mount LVM Volume in Linux

Its possible add a LVM volume on the fly. The steps would involve formatting the newly added disk with LVM and creating a mount point and adding the new volume to it. The whole process would involve creating Physical Volume followed by Volume group and then assigning logical volume and mounting it to a mount point.


Add/Detect a new disk in a Linux VM dynamically without rebooting

Its possible to add a disk dynamically (without reboot) in a Linux host in Virtual Environment by following some simple steps in this article. In a Virtualized world there is a frequent requirement for adding extra disks/space on the fly, as and when required with “Downtime” being a BIG NO NO….

Once you have added a new disk using vSphere Client interface for the host, go ahead and scan the iSCSI Bus Channel.

Linux RHEL / CentOS


In Linux when you try to SSH it may at times give you this warning that REMOTE HOST IDENTIFICATION HAS CHANGED. It usually happens when the hostname or IP has changed of a host or the host was rebooted and generated a new fingerprint Key ID. No need to worry, it can be removed by a single command and you would be up and running in no time.

Spacewalk (CentOS Satellite Version)

Install Spacewalk 2.2 on CentOS

This article shows you the steps to install Spacewalk 2.2 (aka Satellite) version on CentOS. To start with the install we need make sure that firewall and hostname and IP are configured correctly. Make sure that these ports are opened in the firewall.

Ports required:
Outbound open ports — 80, 443, 4545
Inbound open ports — 80, 443, 5222 and 5269, 69 udp if you want to use tftp (for kickstart PXE)

RAM requirements — 2GB Minimum , 4GB Recommended

This article will be based on CentOS 6. There is a one click script as well in BASH SCRIPTS section.

Make sure the hostname ,static IP and host entry is setup properly.

Red Hat IDM

Change SUDO LDAP Password

There might be a need to Change SUDO LDAP password whilst managing the SUDO rights centrally through IDM. In this scenario it would be the 1st time you are configuring the SUDO rights. Follow the steps outlined to change the password for master server.

NOTE: Don’t run this on replica instances of IDM as it would be replicated from Master.

Spacewalk (CentOS Satellite Version)

Install and Register Spacewalk Clients

This article shows you How To register Spacewalk Clients to the Spacewalk Server. All you need is to make sure before the registration you are logged in as ROOT and the SSL Cert is downloaded from the server to the client host. There is a Once Click BASH SCRIPT as well you can download.


Setup Nagios Core on CentOS/Red Hat

Setup and Configuration guide for Nagios Core on any Fedora/Linux based OS (incl. CentOS & Red Hat). This guide would allow you to setup Nagios Monitoring Server up and running in roughly 15 mins. The process would involve installing yum packages and then compiling Nagios from source.

NOTE: You need to a be a ROOT user to compile and install Nagios Core.

Debian Wheezy (7)

Install Nagios Core latest version 4.x.x on Raspbian – RasberryPi

Its now possible to install latest Nagios CORE version on Raspbian by following the steps in this article. Before writing this article I Googled for the same but couldn’t find a single article covering install of latest version of Nagios on RasberryPi hence this guide. It has been fully tested and working on my personal RasPi.

This guide was originally written for Ubuntu but will work for Raspbian (Debian Wheezy) flavour for RasberryPi as well. It might work for all debian distros but not guranteed, you can try it out yourself.