All About Sharepoint Farms

SharePoint farm: 

In the context of SharePoint, the term 'farm' is used to describe a collection of one or more SharePoint servers and one or more SQL servers that come together to provide a set of basic SharePoint services bound together by a single Configuration Database in SQL.

Server Services and Fault Tolerance: Within a farm, there are several services that run on one or more servers. Some of these services are mandatory and some are optional. Service

Purpose

Fault Tolerance

Windows SharePoint Services Web Application (often referred to as 'Web Server' or 'WFE')

This service is responsible for serving the HTML to clients and routing requests to other services in the farm.

Office SharePoint Server Search in Query Mode (often referred to as 'Query Server')

This service is responsible for executing search queries against a locally stored copy of the index

Yes, this role can exist on multiple servers

Office SharePoint Server Search in Index Mode (often referred to as 'Index Server')

This service is responsible for indexing all of the configured content sources, creating an index and propagating it to every Query server in the farm

No, you can only have 1 Index server for each SSP in the farm. If you have multiple SSPs (not recommended – see SSP section), you can have multiple Index servers, but they have their own set of content sources.

Windows SharePoint Services Search

This service is basically a slimmed down version of the Office SharePoint Server Search service which combines both the Query and Index roles into a single service.

Excel Calculation Services

This service is responsible for performing calculations on Excel workbooks that are stored in the content databases.

Yes, this service can exist on multiple servers.

No. If you have more than one instance of this service in a farm, it will be simply do the same thing as the other servers.

Yes, many instances of this service can exist on the same farm.

Typical Server Placement

Typically there are two or more servers running this service ion a farm.

Things to note / Rules If you are using multiple servers, you must also implement a Network Load Balancing solution (NLB) to balance requests across the servers. You must also use host headers for all web applications in this scenario.

This service is typically placed on each Web Application server in the farm.

Since this service requires a local copy of the index, appropriate disk space is needed to store the index.

This service is typically placed on its own dedicated server.

It is possible to run both the Index and Query roles on the same server. However, in this configuration you cannot have multiple Query servers because when Index and Query are on the same server, propagation of the Index is disabled.

This service is typically not used. If you do run this service in a MOSS farm, it is generally run on the same server as the Index server. This service is typically placed on each Web Application server in the farm initially. However, this is a

If you have a MOSS farm, then the only reason for using this service would be to provide full text search of Help. Although this service does support fault tolerance, it does maintain session-state information, therefore users will stay on the same Excel Calculation Services server for the duration of their session.

Document Conversions Load Balancer Service

This service balances document conversion requests from across the server farm.

No. An application server can only have a single Document Conversions Load Balancer Service enabled.

Document Conversions Launcher Service

This service schedules and initiates the document conversions on a server.

Yes. Multiple launchers can exist in the same farm.

Windows SharePoint Services Incoming E-Mail

Windows SharePoint Services Outgoing E-Mail

Central Administration

This service is responsible for receiving incoming emails and placing them in email enabled lists. This is not technically a SharePoint service but refers to an SMTP server which SharePoint send outbound email to

This service enables the central administration interface that is required for farm-wide administration

fairly resource intensive role; therefore, it is typically moved to a dedicated pair of servers if the load becomes too heavy. There is typically only one server running this service in a farm. This is typically placed on the Index server This service is typically placed on each Web Application server in the farm.

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If you are using multiple launcher services, they much each have the same set of document conversion applications installed.

Yes, this service can run on multiple servers. However this does have additional configuration. See the 'Things to note' column for details.

This service is typically placed on each Web Application server in the farm.

There are lots of prerequisite steps that must be configured before using this service.

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No, this service can only run on one server in the farm.

Typically, this role is placed on either the Index server or one of the web servers. By default, the first server in the farm will run this service.

The Central Administration web application does run on every Web Application server in the farm; however requests are always routed to the server that is running this service.

Difference between an “Application Server” and “WFE Server”: When SharePoint is installed, you have to select one of three installation options, they are:

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Application Server Complete Web Front End

An 'Application Server' is a server that is capable of running any of the services in the table above apart from the Windows SharePoint Services Web Application service. A 'Web Front End' (sometimes called a WFE) is the opposite in that it can only run the Windows SharePoint Services Web Application service. 'Complete' means that the server can run any SharePoint service.

The reason behind these options is that in some scenarios, very 'thin' web servers may be required which have a very small installation footprint. In this case, it is not desirable to install all of the DLLs etc that are required to run any service apart from the Windows SharePoint Services Web Application – these are true web servers. In my experience, this is a relatively rare scenario and only really relevant when SharePoint is being used to host high traffic internet sites. The problem with selecting anything other than 'Complete' is that it means if you ever change your mind about what services a server can run, you'll need to re-install SharePoint on that server. For that reason alone, I would always recommend that you choose 'Complete' unless you have a very good reason to do otherwise. This means that the terms 'Web Front End Server' and 'Application Server' are often used incorrectly. Unless your server is only running the Windows SharePoint Services Web Application service, it is an Application server. This means that the majority of servers in the majority of farms are actually Application servers. When to have multiple farms? The general answer is that wherever possible, you should have a single farm.

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Physically separate data centers Differing customization approaches and polices Differing support policies and SLAs Development, staging and test environments