經常有人問題什么是Web Farm, 什么又是Web Garden?
他們的有什么區別?
今天我們就來看一下他們之間的區別
我們知道, web server負責處理客戶端的請求然后再返回給他們.
但是,當請求很多的時候,一台服務器可能承受不了, 這個時候,我們就需
要用多台web server來分擔請求的壓力, that is called to divide the traffic among them.
這就是web farm
web farm -- hosting your single web site on multiple web servers over load balancer
通常,我們在web farm的架構中, 不同的web server通過load balancer和虛擬IP進行連接
因為,當請求過來的時候,它最先接觸的是load balancer, LB把請求分發給相關的web server
web garden
首先,我們來了解一下什么是Worker Process, 在IIS中Worker Process(w3wp.exe)負責處理
所有的請求, 相應,緩存等, Application Pool則是Worker Process的容器, 應用程序池用來被用來分割
Worker Process的集合以保證最佳的穩定性
每個應用程序池默認只有一個工作進程, 但是,如果應用程序池包含了多個工作進程,這種方式就叫做
web garden
在IIS6/7中創建web garden的步驟:
IIS6
1) Right Click on Application Pool -> Properties -> Goto Performance Tab
2) In the “Performance Tab” section, you would have one option called “Web Garden”
where worker process sets to “1”, you can set the number of worker
processes that you required
IIS7
1) Right Click on Application Pool -> Go To Advance Settings -> In Process Model section
you will have “Maximum Worker Processes”
2) You can change it more than 1 to make it as a web garden
Advantages of Web Farm
- It provides high availability. If any of the servers in the farm
goes down, Load balancer can redirect the requests to other servers.
- Provides high performance response for client requests.
- Provides better scalability of the web application and reduces the
failure of the application.
- Session and other resources can be stored in a centralized location
to access by all the servers.
Advantages of Web Garden
- Provides better application availability by sharing requests between
multiple worker process.
- Web garden uses processor affinity where application can be swapped
out based on preference and tag setting.
- Less consumption of physical space for web garden configuration.
Session in Web Farm Mode
While using session, requests are distributed among different servers.
By default, session mode is set to In Proc where session data is stored
inside worker process memory. But, in Web farm mode, we can share the
session among all the servers using a single session store location by
making it Out proc (State Server or SQL Server Mode). So, if some of the
servers go down and request is transferred to the other server by the Load
balancer, session data should be available for that request.
Session in Web Garden Mode
When we are using Web garden where request is being taken care of by
different worker process, we have to make the session mode as out process
session mode as described earlier. For Web Garden, we have to configure
the out process within the same server but for different worker process.