Akash Rajvanshi AkashRajvanshi

What is Hypervisor?

A hypervisor is a software that makes virtualization possible. It is also called Virtual Machine Monitor. It divides the host system and allocates the resources to each divided virtual environment. You can basically have multiple OS on a single host system. There are two types of Hypervisors:

Type 1: It’s also called Native Hypervisor or Bare metal Hypervisor. It runs directly on the underlying host system. It has direct access to your host’s system hardware and hence does not require a base server operating system.
Type 2: This kind of hypervisor makes use of the underlying host operating system. It’s also called Hosted Hypervisor.

What is virtualization?

Virtualization is the process of creating a software-based, virtual version of something(compute storage, servers, application, etc.). These virtual versions or environments are created from a single physical hardware system. Virtualization lets you split one system into many different sections which act like separ

Cloud images in Proxmox

A script which automates these steps for multiple distros incl. CoreOS, CentOS, Arch and ALpine

create-cloud-template.sh

Steps for creating an Ubuntu 18.04 cloud template

Using a ready-to-use Ubuntu image

Multiple SSH Keys settings for different github account

create different public key

create different ssh key according the article Mac Set-Up Git

$ ssh-keygen -t rsa -C "[email protected]"

Postgres Export and Import

Export

pg_dump -U [superuser] -Fc [dbname] > db.dump

Import

Run Raspberry Pi 4 from SSD

Introduction

This gist builds on the excellent work done by Graham Garner, Andreas Spiess, and Peter Scargill to make it easy for Makers to install IOTstack on a Raspberry Pi.

One concern with any out-of-the-box Raspberry Pi is the limited lifespan of its SD card. You'd be pretty annoyed if you got your IOTstack up and running, only to find that you were one of the unlucky ones whose SD card wore out in less than six months!

SSDs, on the other hand, while not immune to the same kinds of failure, tend to have projected life expectancies in the hundreds of years.

Arch Linux btrfs install

0. Prerequisites

Latest Arch Linux install iso because those have newer kernels and more bugfixes in btrfs.
Have previous experience with installing Arch (like you can install arch with a blind fold).

1. Parititions

We will ne two of them, one for /boot and the other one will be a btrfs partition with subvolumes.

/dev/sda1 - this will be /boot with vfat filesystem because UEFI or syslinux for legacy BIOS boot


	Questions are not from any actual exam!!!



	Q: Create a job that calculates pi to 2000 decimal points using the container with the image named perl
	and the following commands issued to the container: ["perl", "-Mbignum=bpi", "-wle", "print bpi(2000)"]
	Once the job has completed, check the logs to and export the result to pi-result.txt.

	Solution:

	# Backup
	docker exec CONTAINER /usr/bin/mysqldump -u root --password=root DATABASE > backup.sql

	# Restore
	cat backup.sql \| docker exec -i CONTAINER /usr/bin/mysql -u root --password=root DATABASE

	= Arch Linux step-by-step installation =
	= http://blog.fabio.mancinelli.me/2012/12/28/Arch_Linux_on_BTRFS.html =


	== Boot the installation CD ==

	== Create partition ==

	cfdisk /dev/sda
	* Create a partition with code 8300 (Linux)

	ssh-keygen -t rsa -b 4096 -N '' -C "[email protected]" -f ~/.ssh/id_rsa
	ssh-keygen -t rsa -b 4096 -N '' -C "[email protected]" -f ~/.ssh/github_rsa
	ssh-keygen -t rsa -b 4096 -N '' -C "[email protected]" -f ~/.ssh/mozilla_rsa