Cache

The ADC is capable of caching data within its internal memory and periodically flushes this Cache to the ADC's internal storage. The settings that manage this functionality are provided within this section.

Global Cache Settings

Maximum Cache Size (MB)

This value determines the maximum RAM that the Cache can consume. The ADC Cache is an in-memory cache that is also periodically flushed to the storage medium to maintain cache persistence after restarts, reboots, and shutdown operations. This functionality means that the maximum cache size must fit within the memory footprint of the appliance (rather than disk space) and should be no more than half of the available memory.

Desired Cache Size (MB)

This value denotes the optimum RAM to which the Cache will be trimmed. While the maximum cache size represents the absolute upper boundary of the Cache, the desired cache size is intended as the optimum size that the Cache should attempt to attain whenever an automatic or manual check on the cache size is made. The gap between the maximum and desired cache size exists to accommodate the arrival and overlap of new content between periodic checks on cache size to trim expired content. Once again, it may be more effective to accept the default value (30 MB) and periodically review the size of the Cache under "Monitor -> Statistics" for appropriate sizing.

Default Cache Time (D/HH:MM)

The value entered here represents the life of content without an explicit expiry value. The default caching time is the period for which content without a "no-store" directive or explicit expiry time in the traffic header is stored.

The field entry takes the form "D/HH:MM" – so an entry of "1/01:01" (default is 1/00:00) means to store the ADC will hold the content for one day, "01:00" for one hour, and "00:01" for one minute.

Cachable HTTP Response Codes

One of the cached data sets is HTTP responses. The HTTP response codes that are cached are:

· 200 – Standard response for successful HTTP requests

· 203 – Headers are not definitive but are gathered from a local or a 3rd party copy

· 301 – The requested resource has been assigned a new permanent URL

· 304 – Not modified since the last request & locally cached copy should be used instead

· 410 – Resource is no longer available at the server, and no forwarding address is known

This field should be edited with caution as the most common cacheable response codes are already listed.

Cache Checking Time (D/HH:MM)

This setting determines the time interval between cache trim operations.

Cache-Fill Count

This setting is a helper facility to help fill the Cache when a certain number of 304's have been detected.

Apply Cache Rule

This section allows you to apply a cache rule to a domain:

· Add domain manually with the Add Records button. You must use a fully qualified domain name or an IP address in dotted-decimal notation. Example www.mycompany.com or 192.168.3.1:80

· Click the dropdown arrow and choose your domain from the list

· The list will be populated so long as traffic has passed through a virtual service and a caching strategy has been applied to the virtual service

· Choose your cache rule by double-clicking on the Caching Rulebase column and selecting from the list

Create Cache Rule

This section allows you to create several different caching rules that can then be applied to a domain:

· Click Add Records and give your rule a name and description

· You can either type your conditions in manually or use the Add Condition

To add a condition using the Selection Rulebase:

· Choose Include or Exclude

· Choose All JPEG Images

· Click on the + Add symbol

· You will see that 'include *.jpg' has now been added to the conditions

· You can add more conditions. If you choose to do this manually, you need to add each condition on a NEW line. Please note that your rules will display on the same line until you click in the Conditions box then they will show on a separate line