Request Manager in SharePoint Server 2013 can route and throttle incoming requests to help improve performance and availability. Request Manager is functionality in SharePoint Server 2013 that enables administrators to manage incoming requests and determine how SharePoint Server 2013 routes these requests.
Request Manager uses configured rules to perform the following tasks when it encounters requests:
- Deny potentially harmful requests from entering a SharePoint farm.
- Route good requests to an available server.
- Manually optimize performance.
Request Management feature in SharePoint 2013 manages incoming requests by evaluating logic rules against the user requests in order to determine what/which action to take, and which machine or machines (Targets) in the farm should handle the requests. SharePoint Foundation Web Application Service of SharePoint 2013 handles and responds to all incoming requests through IIS. Load Balancer is used to distribute incoming traffic across all the web front end servers. It is not necessary that all the web front end servers should be serving the incoming requests. Good example for such scenario would be dedicated Crawl Web Front end server. In such cases, Load balancing features will be leveraged to ensure right requests are redirected to the right machines.
During Medium and Large scale hosting, the need for powerful request management becomes very important. Request Management feature of SharePoint 2013 fulfills this need through advanced routing and Throttling.
Request Management is used as a Service instance although there is no associated Service application. All configurations are performed using Windows PowerShell commands. Request Management is scoped and configured on per web application basis. Request Manager’s task is to decide two things: a SharePoint farm will accept a request, and if the answer is “yes”, to which front-end web server SharePoint Server will send it.
There are three logical components of the request manager:
- Throttling (Limit request) and Routing (route request)
- Prioritization (identify the group of servers to handle request)
- Load balancing (Identify the server to handle request).
When a new request is received, Request Manager is the first code that runs in a SharePoint farm. Although Request Manager is installed during setup of SharePoint Server on a front-end web server, the Request Management service is not enabled. You can use the Start-SPServiceInstance and Stop-SPServiceInstance cmdlets to start and stop the Request Management service instance respectively or the Manage services on server page on the SharePoint Central Administration website. You can use theRoutingEnabled or ThrottlingEnabled parametersofthe Set-SPRequestManagementSettings Windows PowerShell cmdlet to change properties of Request Manager.
Request Manager has two supported deployment modes:
- Dedicated Mode :
A set of front-end web servers is dedicated to managing requests exclusively. The front-end web servers that are dedicated to Request Manager are in their own farm (i.e. not a part of the SharePoint farm) that is located between the hardware load balancers (HLBs) and the SharePoint farm. The HLBs send all requests to the Request Manager front-end web servers. Request Manager that runs on these front-end web servers decides to which SharePoint front-end web servers it will send the requests and then routes the requests. Depending on the routing and throttling rules, Request Manager might ignore some requests without sending them to another server. The SharePoint front-end web servers do their normal tasks in processing requests and then send responses back through the front-end web servers that run Request Manager and to the clients.
Note that all farms are set up as SharePoint farms. All front-end web servers in Figure 1 are SharePoint front-end web servers, each of which can do the same work as any other. The difference between the farms is that the Request Manager front-end web servers have Request Manager enabled.
Dedicated mode is good for larger-scale deployments when physical computers are readily available. The ability to create a separate farm for Request manager provides two benefits: Request Manager and SharePoint processes do not compete for resources and you can scale out one without having to also scale out the other. This allows you to have more control over the performance of each role.
- Request Manager and SharePoint processes do not compete for resources.
- You can scale out each farm separately, which provides more control over the performance of each farm.
- Integrated Mode:
In an integrated mode deployment, all SharePoint front-end web servers run Request Manager. Hardware load balancers send requests to all front-end web servers. When a front-end web server receives a request, Request Manager decides how to handle it.
- Allow it to be processed locally.
- Route it to a different front-end web server.
- Deny the request.
Integrated mode is good for small-scale deployments when many physical computers are not readily available. This mode lets Request Manager and the rest of SharePoint Server to run on all computers. This mode is common for on-premises deployments.