Oracle Web Cache Administration and Deployment Guide Release 1.0.2.3 Part Number A86722-03 |
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This chapter describes the steps to initially configure Oracle Web Cache to begin caching application Web server content after installation.
This chapter contains these topics:
To start Oracle Web Cache to begin initial configuration:
webcachectl start
When Oracle Web Cache is first installed, it is set up with default passwords for administration and invalidation. In addition, the computer on which you installed Oracle Web Cache is the default trusted host.
To change the security settings:
administrator
user. The administrator
user has a default password of administrator
set up during installation. Before you begin configuration, change the default password to a secure password.
The Security page appears in the right pane.
The Change Administration User Password dialog box appears.
administrator
in the Old Password field and a new password between four and 10 characters in the New Password and Confirm New Password fields.
invalidator
, whose default password of invalidator
is set up during installation.
The Change Trusted Subnets dialog box appears.
All subnets
Select to allow administration requests from all computers in all the subnets in the network.
This machine only
Select to allow administration and invalidation requests from only this computer.
Enter list of IPs
Select to allow administration and invalidation requests from all IP addresses you enter in a comma-separated list.
webcachectl start|stop
commands.
When the maximum cache memory limit is reached, Oracle Web Cache performs garbage collection. During garbage collection, Oracle Web Cache removes the less popular and less valid documents from the cache in favor of the more popular and more valid documents.
To avoid swapping documents in and out of the cache, it is crucial to configure enough memory for the cache. By default, the memory limit is set to 500 MB, which is sufficient for most caches. To acquire a rough estimate of the memory required for the cache, use the following formula:
(average HTTP object size) * (maximum number of objects you want to cache)
For example, if you want to cache 10,000 objects and the average the size of those objects is 3 KB, then the maximum cache size limit should be set to at least 30 MB.
When setting the maximum memory usage limit, Oracle Corporation recommends setting the limit as close to the operating system's resource limit as possible. If necessary, resize the operating system's resource limit.
The size and maximum number of Web objects, such as GIF, HTML, or PDF, can be determined by:
In addition to the cache size, it is also important to specify the expected load on the Oracle Web Cache server. The expected load is the sum of the maximum number of incoming open connections to the Oracle Web Cache server and the number of outgoing open connections to the application Web servers. When you configure this limit, set a reasonable number. If you set a number that is too high, performance can be affected. To help you determine the number, you can use various tools available for your operating system. For example, the netstat
command on UNIX enables you to determine the number of established connections.
To set resource limits:
For Oracle Web Cache to act as a virtual server for a Web site, configure Oracle Web Cache with information about the Web site, including the host names of the application Web servers. In addition, specify a listening port from which Oracle Web Cache can receive browser requests.
To configure Oracle Web Cache with Web site information:
The Application Web Servers page appears in the right pane.
The Edit/Create Application Web Server page dialog box appears.
When you set the capacity, it assigns a weighted load percentage to the application Web server. The load specifies the percentage of requests that this application Web server will handle. The load percentage is calculated from the following formula:
application Web server capacity / combined capacity
For example, if one application Web server has a capacity of 50 and a second application Web server has a capacity of 40 for a total capacity of 90, then the first server is assigned a load percentage of 55 and the second server is assigned a load percentage of 45.
50/90 = 55% 40/90 = 45%
If this is the only application Web server, the load will be 100 regardless of the capacity.
The maximum number of concurrent connections that an application Web server can handle is determined by load testing the application Web server until it runs out of CPU, responds slowly, or until a backend database reaches full capacity.
If an application Web server fails any time after Oracle Web Cache has started to send a request, then Oracle Web Cache increments the failure counter. The failure counter is reset in the event of a successful application Web server response. A request is considered failed if:
Once the threshold is met, Oracle Web Cache considers the application Web server down and uses other application Web servers for future requests. When an application Web server is down, Oracle Web Cache starts polling the application Web server. It does this by sending requests to the URL specified in the Ping URL field. When Oracle Web Cache is able to successfully get a response from the application Web server without any network errors and the HTTP response code is not less than 100, or equal to 500, 502, 503, 504, it considers that application Web server live again and uses it for future requests.
Oracle Web Cache listens on port 1100 by default. It may be necessary to add an additional listening port if you want to assign Oracle Web Cache a port that an application Web server was previously listening on.
The Oracle Web Cache Listen Ports page appears in the right pane.
The Edit/Create Oracle Web Cache Listen Ports page dialog box appears.
Specify the URLs containing the documents you want Oracle Web Cache to cache.
When Oracle Web Cache is configured, stop it and start it again to read in the new configuration settings. You can stop and start Oracle Web Cache using either Oracle Web Cache Manager or the webcachectl
utility on the computer on which Oracle Web Cache software is installed and configured:
Use Oracle Web Cache Manager... | Use the webcachectl Utility... |
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