Luis Felipe Dominguez Vega lfdominguez

How to mount a qcow2 disk image

This is a quick guide to mounting a qcow2 disk images on your host server. This is useful to reset passwords, edit files, or recover something without the virtual machine running.

Step 1 - Enable NBD on the Host

modprobe nbd max_part=8

Setting up docker to run in a PRIVILEGED LXC container

Set up a privileged container

Create container

Let's call the container docker_test1.

$ sudo lxc-create -t download -n docker_test1
...
Follow the prompts on the screen to set up the new container.

RKE2 commands

Updated on May 29 to accommodate etcd container not having /bin/sh available anymore.

Install

curl -sL https://get.rke2.io | sh
systemctl daemon-reload
systemctl start rke2-server

	Latency Comparison Numbers (~2012)
	----------------------------------
	L1 cache reference 0.5 ns
	Branch mispredict 5 ns
	L2 cache reference 7 ns 14x L1 cache
	Mutex lock/unlock 25 ns
	Main memory reference 100 ns 20x L2 cache, 200x L1 cache
	Compress 1K bytes with Zippy 3,000 ns 3 us
	Send 1K bytes over 1 Gbps network 10,000 ns 10 us
	Read 4K randomly from SSD* 150,000 ns 150 us ~1GB/sec SSD

	#!/bin/bash
	# Convert Markdown to Wordpress blogging format

	# Required program(s)
	req_progs=(ascii2uni pandoc)
	for p in ${req_progs[@]}; do
	hash "$p" 2>&- \|\| \
	{ echo >&2 " Required program \"$p\" not installed."; exit 1; }
	done

	# save this file in /etc/default/unicorn_app
	USER=app_user
	APP_ROOT=/srv/app
	RVM_STRING=2.2.4@app_gemset
	RACK_ENV=production
	UNICORN_OPTS="-D -c /srv/app/shared/config/unicorn.rb -E production"
	DAEMON=unicorn