Iñigo Aldazabal iamc

Looking to create a Software RAID 1 setup for your 2-disk server on Ubuntu Server 20.04?

Let's start with the basics: the official guide by Ubuntu (https://ubuntu.com/server/docs/install/storage) is outdated/wrong. And as of March 2021 it's possible that there's a bug as well with how the bios_grub partitions are created when using multiple disks.

Now on to the solution:

Select "Custom storage layout" when you reach the storage configuration step of the installer.
If the disks have existing partitions, click on each disk under AVAILABLE DEVICES and then select REFORMAT. This will (temporarily) wipe out the partitions.

Setting up a FlexLM service for SystemD

Create directory structure

Create the directory for the flexlm user to use, e.g., /opt/flexlm
Place all the binaries for the licence manager and the licence in a vendor specific subdirectory

At this point you should have something similar to following directory structure:

/opt/flexlm/
└── VENDOR

These instructions were mostly taken from here, though I've modified them to install Python 2.7.15 and the latest setuptools package.

# Install dependencies
yum groupinstall -y 'development tools'
yum install -y zlib-devel bzip2-devel openssl-devel xz-libs wget

# Download the Python source and unpack it
wget https://www.python.org/ftp/python/2.7.15/Python-2.7.15.tgz
tar -xvzf Python-2.7.15.tgz

Latency numbers every programmer should know

L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns
L2 cache reference ........................... 7 ns
Mutex lock/unlock ........................... 25 ns
Main memory reference ...................... 100 ns             
Compress 1K bytes with Zippy ............. 3,000 ns  =   3 µs
Send 2K bytes over 1 Gbps network ....... 20,000 ns  =  20 µs
SSD random read ........................ 150,000 ns  = 150 µs

Read 1 MB sequentially from memory ..... 250,000 ns = 250 µs

	#!/usr/bin/env python3
	# Notify via Discord

	import os
	import requests
	import sys

	USERNAME = "check_mk"
	AVATARURL = "https://checkmk.com/favicon-96x96.png"

	---
	# SSH server settings, in line with https://stribika.github.io/2015/01/04/secure-secure-shell.html
	# Before using, change myhosts to your hosts' nickname and myuser to your username (two instances! make sure you replace both or you'll be locked out of ssh!)
	- hosts: myhosts
	become: true
	remote_user: myuser
	tasks:
	# Key exchange, ciphers and MACs
	- lineinfile: dest=/etc/ssh/sshd_config regexp='^KexAlgorithms' line='KexAlgorithms [email protected],diffie-hellman-group-exchange-sha256'

	## you need to enable tftp under services->tftp

	login via ssh

	su
	cd /usr/local/bin/
	mount -uw /
	wget -O check_mk_agent "http://git.mathias-kettner.de/git/?p=check_mk.git;a=blob_plain;f=agents/check_mk_agent.freebsd;hb=HEAD"

	chmod a+x check_mk_agent

	shell=`/bin/basename $SHELL`
	#shell=`/bin/basename \`/bin/ps -p $$ -ocomm=\``
	if [ -f /opt/soft/apps/lmod/lmod/init/$shell ]
	then
	export PATH=/opt/soft/apps/lua/5.1.4.5/bin:/opt/soft/apps/lmod/lmod/libexec:$PATH
	. /opt/soft/apps/lmod/lmod/init/$shell
	export MODULEPATH='/opt/Modules/modulesfiles'
	for dir in `ls -1 /opt/soft/modules/\| egrep -v '^all$' `
	do
	export MODULEPATH="$MODULEPATH:/opt/soft/modules/$dir"

	#!/usr/bin/env zsh

	function usage() {
	cat <<EOF
	USAGE i3-xephyr start\|stop\|restart\|run
	start Start nested i3 in xephyr
	stop Stop xephyr
	restart reload i3 in xephyr
	run run command in nested i3
	EOF

	# This gist is compatible with Ansible 1.x .
	# For Ansible 2.x , please check out:
	# - https://gist.github.com/dmsimard/cd706de198c85a8255f6
	# - https://github.com/n0ts/ansible-human_log

	# This program is free software: you can redistribute it and/or modify
	# it under the terms of the GNU General Public License as published by
	# the Free Software Foundation, either version 3 of the License, or
	# (at your option) any later version.
	#