A Cache is a storage mechanism that can be defined for the system to act as a "pre-fetching" facility. Documents can be held in this storage area to decrease retrieval time.
Multiple Caches can be defined on a wide area network (WAN) to locally store documents from the system onto local file servers. A document will be retrieved from a cache when the document has been stored in a cache and the workstation is configured to look in the cache. This improves retrieval time since the cache can be set up locally while the actual document is still stored remotely across the WAN.
The interface for placing documents into a cache is through the Workflow module. There are two available actions that can be used in Workflow, Push to Cache and Purge Cache. Only Document Types that have been configured in its settings to allow caching will be moved to a cache on the Push to Cache action. Purge Cache will delete the local copies of documents currently in the cache.
When a document has been retrieved, the left side of the status bar, at the bottom of the document screen, will list the cache from which the document has been retrieved, or it will list the Disk Group storage, volume, and platter copy number. Example:
To Create a Cache:
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In the Configuration module, select Disk Mgmt | Caching. The Local Server File Caches dialog box is displayed.
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The Cache Configuration dialog box lets you specify the physical characteristics of the cache and its purging capabilities.
The Cache Information section describes the physical attributions of the cache. The Purging Information section describes the purging characteristics of the cache.
Caches are initially set at an approximate size. As each document is added to the cache, its size (KB) is added to the cache. If documents are manually removed from the cache, the approximate size will be out of sync with the true stored bytes of documents in the cache. The true size of the cache will be recomputed each time a purge occurs.
Cache Parameter
Description
Path
Displays the location of the cache on the hard drive. If you are not sure of the location, click Browse to search for the location of the cache storage. The cache location must be a location that workstations can access via UNC or DDS.
Approx. Max KBytes
Displays approximately how many kilobytes are available in the cache for file storage. If the number actually stored goes a bit higher than the number configured, there is some leeway.
Current Cache KBytes
Displays how many kilobytes have been used out of the total amount of kilobytes available.
High Water Mark %
Displays the percent of the maximum size to begin purging the cache. If the cache storage hits this percentage level, the timer configured in Workflow will start the process of purging the cache.
Low Water Mark %
Displays the default percent to leave in the cache when the purge has been completed. When the timer finds the cache at the High Water Mark percent ready to purge, the cache will be purged back to the Low Water Mark percent.
For example, if the High Water Mark % was at 55%, and the Workflow timer finds the cache to be at that point, the cache will start to purge until it hits the Low Water Mark %, say 50%. The cache will look for only the oldest documents to purge until it hits its Low Water Mark percent. The cache will now be 50% full.
Last Purge Date
Displays the last time that the cache was purged.
In addition to these steps, the following must be configured for the cache to be successfully configured:
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Document Types that should use the cache must have the Allow File Caching setting selected.
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Users that need to use the cache must have the cache configured in the Client Workstation Options dialog box's Document tab.