maxp

Put these in /etc/sysctl.conf then run sysctl -p to apply them. 

# General gigabit tuning:
net.core.rmem_max = 16777216
net.core.wmem_max = 16777216
net.ipv4.tcp_rmem = 4096 87380 16777216
net.ipv4.tcp_wmem = 4096 65536 16777216
net.ipv4.tcp_syncookies = 1

# this gives the kernel more memory for tcp

MohamedAlaa

tmux shortcuts & cheatsheet

start new:

tmux

start new with session name:

tmux new -s myname

denji

Moved to git repository: https://github.com/denji/nginx-tuning

NGINX Tuning For Best Performance

For this configuration you can use web server you like, i decided, because i work mostly with it to use nginx.

Generally, properly configured nginx can handle up to 400K to 500K requests per second (clustered), most what i saw is 50K to 80K (non-clustered) requests per second and 30% CPU load, course, this was 2 x Intel Xeon with HyperThreading enabled, but it can work without problem on slower machines.

You must understand that this config is used in testing environment and not in production so you will need to find a way to implement most of those features best possible for your servers.

kennwhite

Recipe for enabling billing access in AWS to a less privileged user

As *Root/Master* account owner:

	1. Log into: https://console.aws.amazon.com  (NOT IAM!)

	2. My Account/Personal Information

	3. Set security challenge questions (fav color/dog/movie, etc.)

kimus

UFW

I use Ubuntu’s Uncomplicated firewall because it is available on Ubuntu and it's very simple.

Install UFW

if ufw is not installed by default be sure to install it first.

vongosling

LInux

Three system configuration parameters must be set to support a large number of open files and TCP connections with large bursts of messages. Changes can be made using the /etc/rc.d/rc.local or /etc/sysctl.conf script to preserve changes after reboot.

1. /proc/sys/fs/file-max: The maximum number of concurrently open files.

fs.file-max = 1000000

2. /proc/sys/net/ipv4/tcp_max_syn_backlog: Maximum number of remembered connection requests, which are still did not receive an acknowledgment from connecting client. The default value is 1024 for systems with more than 128Mb of memory, and 128 for low memory machines.

net.ipv4.tcp_max_syn_backlog = 3240000

3. /proc/sys/net/core/somaxconn: Limit of socket listen() backlog, known in userspace as SOMAXCONN. Defaults to 128.

net.core.somaxconn = 3240000

jkreps

Producer

Setup
bin/kafka-topics.sh --zookeeper esv4-hcl197.grid.linkedin.com:2181 --create --topic test-rep-one --partitions 6 --replication-factor 1
bin/kafka-topics.sh --zookeeper esv4-hcl197.grid.linkedin.com:2181 --create --topic test --partitions 6 --replication-factor 3

Single thread, no replication

bin/kafka-run-class.sh org.apache.kafka.clients.tools.ProducerPerformance test7 50000000 100 -1 acks=1 bootstrap.servers=esv4-hcl198.grid.linkedin.com:9092 buffer.memory=67108864 batch.size=8196

inhumantsar

KEYBINDINGS
       byobu keybindings can be user defined in /usr/share/byobu/keybindings/ (or within .screenrc if byobu-export was used). The  common  key  bindings
       are:

       F2 - Create a new window

       F3 - Move to previous window

       F4 - Move to next window

ssmythe

======
Videos
======

DevOps

  What is DevOps? by Rackspace - Really great introduction to DevOps
    https://www.youtube.com/watch?v=_I94-tJlovg

  Sanjeev Sharma series on DevOps (great repetition to really get the DevOps concept)

miraleung

Added gparted instructions to extend the virtual disk to fork from christopher-hopper/vm-resize-hard-disk.md.

Resize a Hard Disk for a Virtual Machine

Our Virtual Machines are provisioned using Vagrant from a Linux base box to run using VirutalBox. If the Hard Disk space runs out and you cannot remove files to free-up space, you can resize the Hard Disk using some VirtualBox and Linux commands.

Some assumptions