About Site Configuration Oracle Fusion Middleware Online Documentation Library

2-4 Oracle Fusion Middleware Administrators Guide for Oracle Web Cache Most customers leave this setting to the default which is 500 MB. If want to change the default, perform the following steps to determine the maximum amount of memory required: 1. Use the following formula to determine an estimate of the maximum memory, in bytes, needed 1.25TotalDocs AvgDocSize8192+1 8192 + 16384 In the formula: ■ .25 accounts for the run time memory overhead. ■ TotalDocs is the total number of objects you intend to store in the cache. ■ AvgDocSize is the average size of objects, in bytes, you intend to store in the cache. You can determine the average size by viewing the following metrics on the Performance Summary page. – Performance of each Site with Summary site Cache Size – Performance of each Site with Summary site Number of Cached See Section 8.4 for further information about the Performance Summary page. 2. Convert the result to megabytes. 3. Specify the estimated memory in the Oracle Web Cache configuration. See Section 2.11.5 . 4. Use a simulated load or an actual load to monitor the cache to see how much memory it really uses in practice. Remember that the cache is empty when Oracle Web Cache starts. For monitoring to be valid, ensure that the cache is fully populated. That is, ensure that the cache has received enough requests so that a representative number of objects are cached. The Performance Summary page of Fusion Middleware Control provides information about the current memory use and the maximum memory use. To access this page: a. Navigate to the Web Cache Home page in Fusion Middleware Control. See Section 2.6.2 .

b. From the Web Cache menu, select Monitoring and then Performance

Summary .

2.3.2 Maximum Incoming Connections

In addition to the cache size, it is important to specify a reasonable number for the maximum connection limit for the Oracle Web Cache server. The default is 500. If you set a number that is too high, performance can be affected, resulting in slower response time. If you set a number that is too low, Oracle Web Cache serves fewer Note: Even though you specify that certain objects should be cached, not all of the objects are cached at the same time. Only those objects that have been requested and are valid are stored in the cache. As a result, only a certain percentage of your objects are stored in the cache at any given time. That means that you may not need the maximum memory derived from the preceding formula. Getting Started with Administering Oracle Web Cache 2-5 fewer concurrent requests. You must strike a balance between response time and the number of requests processed concurrently. To help determine a reasonable number, consider the following factors: ■ The maximum number of clients you intend to serve concurrently at any given time. ■ The average size of a page and the average number of requests for page. ■ Network bandwidth. The amount of data that can be transferred at any one time is limited by the network bandwidth. ■ The percentage of cache misses. If a large percentage of requests are cache misses, the requests are forwarded to the application Web server. Those requests consume additional network bandwidth and result in longer response times. ■ How quickly a page is processed. Use a network monitoring utility, such as ttcp or LoadRunner, to determine how quickly your system processes a page. ■ The cache cluster member capacity, if you have a cache cluster environment. The capacity reflects the number of incoming connections from other cache cluster members. See Section 3.6.3 to configure this setting in Fusion Middleware Control and Section 3.7.1 to configure this setting in Oracle Web Cache Manager. Use various tools, such as those available with the operating system and with Oracle Web Cache, to help you determine the maximum number of connections. For example, the netstat -a command on UNIX and Windows operating systems enables you to determine the number of established connections; the ttcp utility enables you to determine how fast a page is processed. The Web Cache Home page and the Performance Summary page in Fusion Middleware Control provide statistics on hits and misses. From Web Cache menu, select Home and Monitoring Performance Summary to access these page. Do not set the value to an arbitrarily high value, because Oracle Web Cache sets aside some resources for each connection, which could adversely affect performance. For many UNIX systems, 5000 is usually a reasonable number. To specify the maximum number of incoming connections, see Section 2.11.5 . Connections on UNIX On most UNIX platforms, each client connection requires a separate file descriptor. Oracle Web Cache tries to reserve the maximum number of file descriptors Max_ File_Desc when it starts. If the Oracle Web Cache webcached executable is run as root, you can increase this number. For example, on Sun Solaris, you can increase the maximum number of file descriptors by setting the rlim_fd_max parameter. If the webcached executable is not run with the root privilege, Oracle Web Cache fails to start. On most UNIX platforms, each client connection requires a separate file descriptor. The Oracle Web Cache server attempts to reserve the maximum number of file descriptors when it starts. If you have root privileges, you can increase this number. For example, for the LINUX Red Hat Operating System you can increase the maximum number of file descriptors by modifying Oracle Web Cache users file descriptors limits in etcsecuritylimits.conf. For example to allow the user WC_USER to have 4092 connections, in the etcsecuritylimits.conf file add the following entries: WC_User soft nofile 4092 WC_User hard nofile 4092