Administer cache settings and profiles
Updated: July 24, 2008
Applies To: Office SharePoint Server 2007
Microsoft Office SharePoint Server 2007 provides the following three types of caching options that enable you to maximize performance for your Web applications and sites:
Page output cache
The page output cache stores rendered output of all controls in a given page, and also stores several different versions of this pre-rendered page. Page output cache settings can be configured at the site collection level, at the site level, and for page layouts. You must be using the Publishing feature on your site in order to use page output caching. The page output cache is turned off by default.
Because the page output cache is stored in memory, it is important to have sufficient memory on the front-end Web server.
After a page is first rendered for a user, each subsequent time that the user views that page, the page loads faster because the controls on the .aspx page do not need to run again to generate the HTML. The amount of time required to render the page is reduced. The page output cache can improve server performance because it reduces server control activities and calls to the database.
When a page request is rendered from the page output cache, the server does not need to do the following work:
Fetch the source code or any Web Part components from the database.
Reload and render each control.
Query any database servers that the control might rely on for its data.
Anonymous and authenticated cache profiles are used by the page output cache to store configuration settings for caching at the site collection level, the individual site level, or a master page level.
A cache profile defines the following types of cache behavior:
The length of time that items should be held within the cache
The security trimming policy
The expiration of settings, such as duration and changes
The partition of a cache based on user permission, user rights, and other custom variables
Because a cache profile can be centrally defined for a site collection, you can update a profile in one place and the change is immediately implemented across the site collection.
The object cache reduces the amount of traffic between the Web server and the SQL database by storing objects—such as lists and libraries, site settings, and page layouts—in memory on the front-end Web server. As a result, the pages that require these items are able to be rendered quickly, increasing the speed with which pages are delivered to the client browser. The object cache is on by default.
Because the object cache is stored in memory, it is important to have sufficient memory on the front-end Web server.
You can optimize the object cache for a site collection by specifying several settings:
The size of the object cache.
Specifying a larger number can enhance performance for some large sites at the cost of memory on each front-end Web server.
When to check the server for changes in a cross-list query.
A cross-list query is one that displays content from multiple lists or libraries. Some Web Parts, particularly the Content Query Web Part, often display items from multiple lists and libraries. You can specify to check the server for every cross-list query or you can specify an amount of time (in seconds) in which the results can be drawn from the cache. This can improve performance, particularly for site collections that contain numerous cross-list queries.
A multiplier to use to retrieve more results than are requested.
The multiplier is used to ensure that all client requests are accommodated in a cross-list query and a valid set of results is delivered.
You can also use the Object Cache Settings page to reset (flush) both the object cache and the disk-based cache on an individual server or for the entire server farm.
The disk-based cache stores items that help render Web pages in the browser, such as .jpg, .js and .css files. Unlike the object and page output caches, which are stored in memory on the front-end Web server, the disk-based cache is stored directly on the hard drive of the server. The first time a Web page is called, these items are copied from the database to the hard drive, and all subsequent requests for those items are then served from the hard drive of the Web server. The disk-based cache is off by default.
You enable disk-based caching in the Web.config file in the Web application to which you want to apply it. The changes you make to the Web.config file will be applied to all site collections within the Web application.
Disk-based caching is referred to as BLOB (binary large object) caching within the Web.config file.
Page output cache settings must be configured at the site collection level before the site level. Therefore, perform these procedures in the following order:
To manage other cache settings, you can perform the following procedures in any order:
For information about:
Types of caching, network planning and security considerations, see Additional performance and capacity planning factors (Office SharePoint Server).
Common usage scenarios around performance and capacity planning, see Estimate performance and capacity requirements (Office SharePoint Server).
Content caching of pages with personalized content, see Plan security for an external anonymous access environment (Office SharePoint Server).