li-ch

#System Design Cheatsheet

Picking the right architecture = Picking the right battles + Managing trade-offs

##Basic Steps

1. Clarify and agree on the scope of the system

• User cases (description of sequences of events that, taken together, lead to a system doing something useful)
  • Who is going to use it?
  • How are they going to use it?

li-ch

#!/usr/local/bin/python
import subprocess

procs = []
pids = []
i = 0
for size in [5, 20, 93]:
    proc = subprocess.Popen(["./ver-{}/cloud_burst/target/release/server".format(size), "127.0.0.1:1000{}".format(i)],
                            shell=True)
    i += 1

li-ch

list all tcpdump process:

pgrep tcpdump

kill all tcpdump process:

pkill tcpdump

tcpdump -ttttt -w temp.pcap -i eth2 -s 100 dst 192.168.16.1

li-ch

#!/bin/bash

nmap 192.168.2.0/24 -n -sP | grep report | awk '{print $5}'

li-ch

li@sing:~$ sudo ssh -S /var/run/ssh-tun2-tunnel-control -M -f -w 2:2 143.89.191.40 true

li@sing:~$ ip route show
default via 143.89.244.126 dev eth0
10.2.0.1 dev tun2  proto kernel  scope link  src 10.2.0.2
10.8.0.0/24 via 10.8.0.2 dev tun0
10.8.0.2 dev tun0  proto kernel  scope link  src 10.8.0.1
143.89.244.64/26 dev eth0  proto kernel  scope link  src 143.89.244.107
192.168.1.0/24 dev eth1  proto kernel  scope link  src 192.168.1.254
192.168.2.0/24 via 10.2.0.1 dev tun2

li-ch

#!/bin/bash
cat after.log | egrep '(r|t)x_pause_dur' | tr -s ' ' | cut -d ' ' -f 3

# print log file to std
# filter out the insterested part
# trim out the unnecessary parts
# cut the output into parts, and select the column.

li-ch

mount 192.168.2.254:/srv/nfs4/home /home
mount 192.168.2.254:/srv/nfs4/opt /opt

li-ch

---
# ^^^ YAML documents must begin with the document separator "---"
#
#### Example docblock, I like to put a descriptive comment at the top of my 
#### playbooks.
#
# Overview: Playbook to bootstrap a new host for configuration management.
# Applies to: production
# Description: 
#   Ensures that a host is configured for management with Ansible.

li-ch

Sample playbook for getting shell output from stdout at distributed clients.

---
-
  hosts: all
  gather_facts: no
  tasks:
    - shell: nmap 192.168.101.0/24 -n -sP | grep report | awk '{print $5}'
      register: regnmap
 

li-ch

import networkx as nx
import random
import numpy as np

for k in range(5,64,10):
    for m in range(1000,10001,2000):
        mean_time_between_failure = m # unit is hour
        failRate = 1/mean_time_between_failure
        time_quantum = 1 # hour