Benchmarking Linux disks with fio utility

https://www.linux.com/learn/inspecting-disk-io-performance-fio

http://blog.dbi-services.com/flexible-io-simulating-database-like-io-activity-without-an-installed-database/

Exploring hardware

Restrict network access to docker container

Debugging iptables

Disable ssh host verification

Sudoers syntax

http://unix.stackexchange.com/questions/18877/what-is-the-proper-sudoers-syntax-to-add-a-user

Regex in bash

How to clear disk cache

$ free -m
 total used free shared buffers cached
Mem: 1504 1471 33 0 36 801
-/+ buffers/cache: 633 871
Swap: 2047 6 2041

$ echo 3 | sudo tee /proc/sys/vm/drop_caches 
3

$ free -m
 total used free shared buffers cached
Mem: 1504 763 741 0 0 134
-/+ buffers/cache: 629 875
Swap: 2047 6 2041

vmstat output explained

Performance Tools by Brendan Gregg