Server Roles in SharePoint 2013

Some points I captured from Microsoft Training about server roles

Web Front End servers

Web Front End (WFE) servers form the connection point for clients that request content or services from

SharePoint. Every request from a client is directed to a WFE server, and every response to a client is sent

from a WFE server. This means that all client requests place some load on WFE servers. A WFE server is

responsible for:

• Processing incoming requests through IIS.

• Requesting any data from service applications and databases that is required to service the request.

• Processing the data returned by service applications and databases.

• Compiling responses as ASP.NET pages and sending the responses to the requestor.

In small farms, WFE servers often perform application roles in addition to the WFE role. WFE servers do

not require large quantities of disk storage; instead, they rely heavily on processor power and memory for

performance. Some service applications, especially those relating to business intelligence (BI) functionality, can significantly increase processor and memory load on WFE servers, even when the service applications are running on dedicated application servers.

To improve the performance of page rendering and client access, you can add more WFE servers to the

farm and implement network load balancing and request management.

Application servers

Application servers host service applications. You can distribute service applications between the servers in your server farm to manage load. The specific hardware demands imposed by service applications vary

both by the type of service application and by how the service application is used. However, as a general

rule, service applications do not require disk space on the application server; instead, they may impose

significant processor and memory demands. To mitigate these demands, you should:

• Conduct regular monitoring of processor and memory load on application servers.

• Distribute service applications between the available application servers to allocate server load evenly

Search servers

The search service application can add significantly to the resource requirements of a SharePoint 2013

server farm. Although the components of the search service are technically the responsibility of

application servers, many large SharePoint deployments use dedicated servers to run components of the

search service. In SharePoint 2013, the search service consists of the following major components:

• The index component. The search index is divided into one or more index partitions. Each partition

stores part of the search index as a set of files on disk. Index partitions can be allocated (and

replicated) across individual servers in a server farm. The index component writes index items received

from the content processing component and issues result sets to the query processing component.

The index component can place high demands on memory and disk input and output (I/O).

• The query processing component. The query processing component receives search requests from a

WFE server. It processes the request and sends it to the index component, which returns a result set. It

then processes the result set and returns it to the WFE server as search results. Typically, the query

processing component places high demands on memory and processor power.

• The search administration component. The search administration component manages the processes

and timer jobs that underpin the search service. In isolation, the search administration component

does not place heavy demands on hardware.

• The crawl component. The crawl component browses content sources on a scheduled basis and

provided crawled content, together with any associated metadata, to the content processing

component. The crawl component places very heavy demands on the available processor power and

consumes a large amount of I/O bandwidth.

• The content processing component. The content processing component receives content and

metadata from the crawl component. It transforms the crawled items into index-ready items, for

example by parsing documents and mapping crawled properties to managed properties. Typically,

the content processing component places high demands on memory and processor power.

• The analytics component. The analytics processing component analyzes crawled items and how the

search service is used. It writes the results of this analysis to the analytics reporting database. The

analytics component can place high demands on memory and processor power, and it consumes

significant I/O bandwidth.

Each of these components can be allocated to one or more application servers in the server farm.

Database servers

Database servers in a SharePoint 2013 farm run SQL Server 2012 or SQL Server 2008 R2 and host a range

of SharePoint databases, including the configuration database, content databases, and service application

databases. The database server role is generally not as processor-intensive as other server roles. However, database servers typically experience heavy memory load and heavy I/O load. When you configure or maintain a database server, you should ensure that sufficient memory is available, that sufficient storage is available, and that your storage media is fast enough to prevent I/O bottlenecks.