CacheGuard-OS
User's Guide - Version UF-2.0.2

Web Cache

Cached Object Size

For performance reasons, the appliance caches only objects with a size greater than or equal to a lower limit and lesser than or equal to an upper limit. So objects smaller than or larger than those limits are not saved in the persistent cache memory. Upper and lower limits may be modified for specific needs. Please note that these parameters should be manipulated with caution: caching all objects (even less than 1 KB) may decrease performances as the appliance would spend to read/write from/to the cache while network i/o may be faster (even with a low bandwidth network connection). Similarly caching too big objects may rapidly saturate the cache with objects fetched only by a few people. To cache only objects between 1 KB and 128 MB use the following commands (sizes should be specified in Kilo Bytes):

• cache object 1 131072
• apply

We advise that you leave this parameter at its default values (i.e. 1 KB and 5120 KB). In modifying these values it is assumed that you know what you are doing for your specific needs.

Caching bigger Object

I some cases it is useful to cache a very big object that are used by several people like a smart phone OS (as updates are very frequent nowadays). Caching very big objects (larger than 256 MB) is not possible by increasing the upper limit for common objects as the maximum value for that upper limit is 262144 KB (256 MB).

In this case you can activate the big object caching. This feature allows you to reserve a limited area on your cache to store objects bigger than the upper limit for common objects. The size of this area varies depending on the size of your hard drive(s) and other parameters given during the installation. This feature allows you to cache very big objects without the disadvantage of having your total cache saturated by very big objects.

To activate the caching of big objects from 131073 KB up to 2 GB use the following commands:

• cache bigobject on 131073 2097152
• apply

Forcing a URL Load

In some cases (buggy Web sites, forcing the update...) an URL needs to be explicitly reloaded into the cache. To force the loading of a URL use the command "cache" followed by the argument "loadurl" and the URL to fetch. For instance to force the loading of the URL http://www.example.com/example.html use the command:

• cache loadurl http://www.example.com/example.html

Displaying a Report

If you want to know how much the caching module contributes to optimizing your internet bandwidth you can use the command "cache report". This command displays the total cache size, the cache size for big objects, the amount of the cache space filled by Web objects and the amount of data retrieved from the cache compared to all data passing through the system. To display the cache report use the following command:

• cache report