This section describes the performance and scalability limits of Windows SharePoint Services. The goal is to provide administrators with the information they need to purchase hardware, choose a server configuration, and manage the capacity of their Windows SharePoint Services deployment.

There are two kinds of limits in Windows SharePoint Services:

• Throughput limits - The number of transactions per second that a given server configuration for Windows SharePoint Services can handle. This limit determines the number of users who can simultaneously use a given server resource.
  
• Scale limits - The number of objects that can be created in a given scope (for example, the number of documents per folder). This limit determines the server configuration required to host a given number of objects.
  

More about the tested hardware and software

The following hardware was used to gather the performance and scalability data in Capacity Planning.

The Web server computers were Compaq DL360s with two 1 gigahertz (GHz) Pentium 3 processors and 1 gigabyte (GB) of memory. The computers were running a prerelease version of Microsoft Windows Server 2003, Enterprise Edition.

The database server computers were Compaq DL380s with two 1 GHz Pentium 3 processors and 2 GB of memory. The computers were running Microsoft SQL Server 2000 SP 2 and a prerelease version of Windows Server 2003, Enterprise Edition.

The goal of the throughput testing is to measure the number of transactions per second that a server running Windows SharePoint Services can handle. The measured throughput is then used to extrapolate the number of simultaneous users by using a model of typical user behavior.

The Windows SharePoint Services team tests throughput by using automated load generation tools that work in machine time, not user time. In other words, real user behavior is not modeled in the test lab; rather, server capacity is measured using fictitious "super users" who issue requests as fast as the server can respond.

There are two main variables in the throughput testing:

• Transaction mix - The mix of user transactions, such as "browse home page," "save document," and "edit list item."
  
• Server configuration - The configuration, such as a single server or a server farm with two Web servers.
  

The transaction mix is the mix of different user operations seen by the server, such as "browse home page," "edit document," and so on.

The Windows SharePoint Services team tests two different transaction mixes:

• Read/write - This is the typical Windows SharePoint Services site operation mix. Most of the load is browsing to pages and documents in the site, but there is a substantial amount of list and document authoring as well. For details on the read/write operation mix, see the table in the "More about the tested read/write transaction mix" section in this topic.
  
• Read-only - This is the typical load of a reference site where the data on the server is changing very slowly. For this mix, the entire test load is on the home page of the site. The home page is one of the most expensive pages to render, so this is a fairly conservative read-only load.
  

The following table describes the mix of operations that make up the read/write transaction mix. The Windows SharePoint Services team counts only meaningful end-user operations in the throughput numbers, but the load on the server includes supporting transactions as well, such as getting the images, style sheets, and JavaScript files for the home page.

More about the tested read/write transaction mix

Table: Read/Write Transaction Operations Mix by Percentage

End-user operation	Percentage
Get home page	9.0 percent
Get list page (HTML)	9.0 percent
Get list page (grid)	9.0 percent
Get list form	6.0 percent
Get static document	15.0 percent
Insert list item	1.5 percent
Edit list item	1.5 percent
Delete list item	1.5 percent
Insert document	1.5 percent
Open document for edit	1.5 percent
Save document	1.5 percent
Delete document	1.5 percent
List URLs	1.5 percent
Short term check-out	15.0 percent
Get cached document	15.0 percent
404 errors	10.0 percent

The server configuration describes how computers are configured to run the site. Windows SharePoint Services supports a server farm design where multiple Web servers can be used to serve the same content.

The solution tests the following configurations:

• Light - Each user generates about two transactions per minute, on average, including supporting transactions. With this model, each transaction-per-second supports about 90 users.
  
• Medium - Each user generates about four transactions per minute, on average. With this model, each transaction-per-second supports about 50 users.
  
• Heavy - Each user generates about ten transactions per minute, on average. With this model, each transaction-per-second supports about 20 users.
  

The following two tables show the throughput results for each transaction mix, server configuration, and user model.

Table: Throughput Results for Read/Write Mix

Server configuration	Transactions per second	Heavy user count	Medium user count	Light user count
Single	49	980	2,450	4,410
1 by 1	69	1,380	3,450	6,210
2 by 1	121	2,420	6,050	10,890
3 by 1	136	2,720	6,800	12,240
4 by 1	140	2,800	7,000	12,600
5 by 1	140	2,800	7,000	12,600
6 by 1	140	2,800	7,000	12,600
7 by 1	140	2,800	7,000	12,600
8 by 1	140	2,800	7,000	12,600

Table: Throughput Results for Read-only

Server configuration	Transactions per second	Heavy user count	Medium user count	Light user count
Single	75	1,500	3,750	6,750
1 by 1	77	1,540	3,850	6,930
2 by 1	154	3,080	7,700	13,860
2 by 1	154	3,080	7,700	13,860
2 by 1	154	3,080	7,700	13,860
2 by 1	154	3,080	7,700	13,860
2 by 1	154	3,080	7,700	13,860
2 by 1	154	3,080	7,700	13,860
3 by 1	225	4,500	11,250	20,250
4 by 1	280	5,600	14,000	25,200
5 by 1	293	5,860	14,650	26,370
6 by 1	307	6,140	15,350	27,630
7 by 1	308	6,160	15,400	27,720
8 by 1	309	6,180	15,450	27,810

Adding Web servers to the server farm increases the capacity of the server farm, but only to a certain point:

• For the read-only transaction mix, the capacity of the server farm increases steadily for up to four Web servers and stops increasing at six Web servers.
  
• For the read/write transaction mix, the capacity does not increase beyond four Web servers because the throughput is now limited by the one database server computer. Extending capacity beyond this point requires adding another database server to the server farm.