About content cache areas
Content cache areas provide a local storage of frequently accessed documents accessible over a LAN. These content cache areas allow users that are geographically remote from the file storage areas to quickly access frequently requested document content.
Content caching offers the following features:
- Shared cache: Content Engine content cache can be shared by multiple servers. All clients indirectly share the same cache.
- Security settings: Content caching uses the same security as that of the domain.
- Disk space management: Least recently accessed documents are removed on a scheduled basis.
- Preload content when created: You can configure the content cache to automatically load content when it is checked in.
With Enterprise Manager, you can manage the content cache area and assign it to domain resources. Content caching:
- Delivers frequently accessed content over a LAN.
- Speeds up access by maintaining document content in a geographically local cache.
- Can be shared by multiple Content Engine servers within a single site.
Content caching objects
With Enterprise Manager, you can configure the following content cache objects:
- Content cache area: holds temporary copies of files retrieved over a network from file storage areas, as well as content retrieved from database storage areas.
- Content cache configuration: determines how a single content cache area is assigned to a domain object, such as a server instance, virtual server, site, or domain.
Content retention
Documents remain in the content cache area based on the setting of the Content Lifespan property. The configurable Content Lifespan setting specifies the number of days that a document can remain in cache since its last access. The default value is 14 days. When the Content Lifespan is exceeded, the document can be removed from content cache. There is no time limit on how long a document can remain in cache as long as it is accessed periodically.
NOTE If you have sensitive or confidential documents, you should consider whether caching is appropriate. Files are not automatically deleted from the content cache area when the document is deleted from the storage area. Until they have reached their Content Lifespan setting, files that reside in the content cache area remain available to users with access to the content cache server.
Pruning
Pruning refers to the removal of cache files on a least-recently-used basis. Pruning helps keep the overall size of the cache under the configured pruning threshold. For more information on pruning thresholds, see Content cache area properties (Processing tab).
There are two types of pruning operations that can occur:
- Periodic pruning occurs automatically halfway through the period specified by the Content Lifespan setting, and scans the content cache area for documents that have exceeded the Content Lifespan setting.
- Mandatory pruning occurs automatically when the content exceeds one of the following.
- Pruning Threshold Size (in KB)
- Pruning Threshold Elements
The mandatory pruning operation removes the percentage of files (elements) or space (size), configured on the percentage to prune property. For more information on configuring the pruning properties, see Content cache area properties (Processing tab).
Managing content cache areas
The following content cache configuration guidelines can help improve your system performance:
- Configure one content cache area to be shared on a high-speed network by servers in the same site within the domain.
- Avoid locating a content cache area remotely over a slow-speed network. You might consider disregarding this guideline only if it takes longer to retrieve content from a local database than it does to display that content from a remote content cache area.
- Do not store documents in a folder designated as a content cache area. Storing other documents in that folder consumes space required for content caching.
- Set up the pruning threshold parameters (Size, Number of Elements, and Percentage to Prune) to optimize system performance. Before configuring a content cache area, consider the following information:
- The amount of available space on the content cache server.
- If the content cache server has a very large hard drive, you can afford to enlarge the maximum space for content caching. Doing this minimizes network traffic and reduces network access time by keeping the most recently accessed content in local cache.
- If your caching server has limited space available, reduce the maximum space for content caching. Allocating more space than the server has available can tie up system resources and slow down system performance.
- Determine the number of files frequently accessed by users. Increase that number by 5-10% to account for the maximum number of files allowed in the cache.
- If your system maintains relatively small files, you can allow a greater number of files in cache.
- Don't enable Preload On Create if a content cache area is intended for a site that is heavily used to create new documents if those documents are not subsequently retrieved.
- Review your system requirements before setting the Content Lifespan interval. The shorter the lifespan is, the more often content is removed and re-fetched. The longer the lifespan is, the more deleted content occupies the content cache area..
- Disable content caching for sites that use confidential documents. If you allow content caching, files can remain in cache and be accessible to users with access to the server, even after being purged from the original file storage area.
- Analyze the content cache settings periodically and modify the configuration properties as necessary. For example, if you experience system slowdown because users are accessing more files than configured in the content cache area, increase the maximum number of files allowed.