flyinweb's blog

Version 1.0
Author: Falko Timme <ft [at] falkotimme [dot] com>
Last edited 05/15/2009

This article explains how to set up a two-node load balancer in an active/passive configuration with HAProxy and heartbeat on Debian Lenny. The load balancer sits between the user and two (or more) backend Apache web servers that hold the same content. Not only does the load balancer distribute the requests to the two backend Apache servers, it also checks the health of the backend servers. If one of them is down, all requests will automatically be redirected to the remaining backend server. In addition to that, the two load balancer nodes monitor each other using heartbeat, and if the master fails, the slave becomes the master, which means the users will not notice any disruption of the service. HAProxy is session-aware, which means you can use it with any web application that makes use of sessions (such as forums, shopping carts, etc.).

LVS搭建高可用性Web负载均衡服务器(两台LVS服务器单网卡，兼作realserver)　实际应用了大半年了,使用mcast做多播检测,由于vlan太大偶尔出了点问题,（改ucast或改mcast eth1 ...）解决问题。

什麼是 MySQL Master-Master Replication Manager(MMM)?

• MMM (MySQL Master-Master Replication Manager) 是整合 Script 做 監控/管理 MySQL Master-Master replication cluster 的設定配置.
• Master-Master 的意思不是同時有兩台 Master 應付寫入的動作, 而是要做備援, 若 Master 死掉, 可於最短的時間內(幾秒內), 將備援的 Master 替換上線, 而這台備援的 Master, 平常也可以當 Slave (Reader).
• 當 Slave 的 Replication Failed 時, 會自動讓此 Slave 停止提供服務, 避免不同步的狀況發生.
• MMM 可解決 Master 死掉時, 需要停機或停止所有寫入的問題.

一、前言: 

Master-Slave的数据库机构解决了很多问题，特别是read/write比较高的web2.0应用：

1、写操作全部在Master结点执行，并由Slave数据库结点定时(默认60s)读取Master的bin-log

2、将众多的用户读请求分散到更多的数据库节点，从而减轻了单点的压力

这是对Replication的最基本陈述，这种模式的在系统Scale-out方案中很有引力(如有必要，数据可以先进行Sharding，再使用replication)。

Despite of my high load at work I decided to release mmm-1.0-pre2 today. There are some small, but critical fixes added and much more coming next week (or little bit later if mysqlconf will take more time than I think).

After the first alpha release I’ve received lots of emails, some messages in mmm-devel mail list and even some bug reports in Google Code bug tracking. One of the most asked things was documentation. So, I decided to write some posts in this blog (sorry to non-sql-related readers) and them compose some docs for final release using these posts and comments from readers. This post will be first in mmm-series and will describe how to use mmm in simple master+master scheme where one master accept write requests and both masters accept read requests. This post will provide you with detailed instructions about MySQL setup, permissions setting, mmm installation and configuration and cluster management.

This example will guide you through a simple IP based load balancing solution that handles ssl traffic.

It appears this configuration wasn’t working with HAProxy version 1.3.20 due to the “option nolinger” feature. I have removed it from the configuration and can confirm it works well with HAProxy v.1.3.15 to v.1.3.20. Because of this, you’ll also notice a significant increase in TIME_WAIT sessions, as well as ip_conntrack_count increasing from ~150 to ~925.