16 Web Cache

You can use Oracle Enterprise Manager to view the overall status of Oracle9IAS Web Cache. You can also use Enterprise Manager to view Oracle9IAS Web Cache performance metrics that have been collected by the Oracle Agent.

16.1 Cache Performance

This metric serves as a container for the Oracle9iAS Cache Performance metrics.

16.1.1 Allocated Cache Memory (%)

The percentage of the maximum cache size that is allocated to cached objects. The maximum cache size is configured in the Resource Limits page of OracleAS Web Cache Manager.

16.1.1.1 Metric Summary

The following table shows how often the metric's value is collected and compared against the default thresholds. The 'Consecutive Number of Occurrences Preceding Notification' column indicates the consecutive number of times the comparison against thresholds should hold TRUE before an alert is generated.

Table 16-1 Metric Summary Table

Target Version	Evaluation and Collection Frequency	Upload Frequency	Operator	Default Warning Threshold	Default Critical Threshold	Consecutive Number of Occurrences Preceding Notification	Alert Text
All Versions	Every 5 Minutes	After Every 12 Samples	>	90	99	2	The cache is using %value%%% of its allocated memory

16.1.1.2 User Action

When the cache size reaches 90 percent, the cache will start forced garbage collection.

16.1.2 Cacheable Misses (% of requests)

The percentage of requests for content which is cachable but was not available in the cache.

16.1.2.1 Metric Summary

The following table shows how often the metric's value is collected.

Target Version	Collection Frequency
All Versions	Every 5 Minutes

16.1.2.2 User Action

Check caching rules configuration in OracleAS Web Cache Manager.

16.1.3 Cached Documents Count

The number of objects stored in the cache, plus the number of objects in transit through the cache. The number includes objects that have expired or have been invalidated but which have not been deleted from the cache. For a cache cluster member, this number represents owned content.

16.1.3.1 Metric Summary

The following table shows how often the metric's value is collected.

Target Version	Collection Frequency
All Versions	Every 5 Minutes

16.1.3.2 User Action

No user action necessary. This metric is intended for informational purposes only.

16.1.4 Compression Savings (%)

The number of bytes that are saved due to in-cache compression as a percentage of the total number of bytes, before compression, in the documents served.

16.1.4.1 Metric Summary

The following table shows how often the metric's value is collected.

Target Version	Collection Frequency
All Versions	Every 5 Minutes

16.1.4.2 User Action

No user action necessary. This metric is intended for informational purposes only.

16.1.5 Data Served (MB/second)

The average number of megabytes served by the cache per second during the current time period.

16.1.5.1 Metric Summary

The following table shows how often the metric's value is collected.

Target Version	Collection Frequency
All Versions	Every 5 Minutes

16.1.5.2 User Action

Specific to your site.

16.1.6 Errors (% of requests)

The percentage of requests that resulted in the cache serving error pages to Web browsers.

16.1.6.1 Metric Summary

The following table shows how often the metric's value is collected.

Target Version	Collection Frequency
All Versions	Every 5 Minutes

16.1.6.2 User Action

Refer to the specific error being served.

16.1.7 Hit Rate Per Second

The average number of requests served by cache content per second during the current time period.

16.1.7.1 Metric Summary

The following table shows how often the metric's value is collected.

Target Version	Collection Frequency
All Versions	Every 5 Minutes

16.1.7.2 User Action

If the number of hits is low, then perform the following:

Review the caching rules configuration in Oacle9iAS Web Cache Manager.
In the Popular Requests page in Oacle9iAS Web Cache Manager, select the Not Cached from the Filter Documents list to view the most frequent misses.

16.1.8 Hits (% of requests)

The percentage of requests resolved by cache content. This percentage should be high, except when objects are being invalidated.

16.1.8.1 Metric Summary

Table 16-2 Metric Summary Table

Target Version	Evaluation and Collection Frequency	Upload Frequency	Operator	Default Warning Threshold	Default Critical Threshold	Consecutive Number of Occurrences Preceding Notification	Alert Text
All Versions	Every 5 Minutes	After Every 12 Samples	<	30	20	3	%value%%% of requests were cache hits

16.1.8.2 User Action

If the percentage of hits is low, then perform the following:

Review the caching rules configuration in Oacle9iAS Web Cache Manager.
In the Popular Requests page in Oacle9iAS Web Cache Manager, select the Not Cached from the Filter Documents list to view the most frequent misses.

16.1.9 Invalidated Objects Per Second

The average number of objects invalidated from the cache per second during the current time period.

16.1.9.1 Metric Summary

The following table shows how often the metric's value is collected.

Target Version	Collection Frequency
All Versions	Every 5 Minutes

16.1.9.2 User Action

The ratio of invalidated objects to invalidation requests can help you determine invalidation performance.

16.1.10 Invalidation Requests Per Second

The average number of invalidation requests processed by the cache per second during the current time period.

16.1.10.1 Metric Summary

Table 16-3 Metric Summary Table

Target Version	Evaluation and Collection Frequency	Upload Frequency	Operator	Default Warning Threshold	Default Critical Threshold	Consecutive Number of Occurrences Preceding Notification	Alert Text
All Versions	Every 5 Minutes	After Every 12 Samples	>	100	120	2	The cache encountered %value% invalidation requests per second

16.1.10.2 User Action

No user action necessary. This metric is intended for informational purposes only. Note that if invalidation is frequent, then performance may be effected.

16.1.11 Misses Per Second

The average number of requests per second for cacheable and non-cacheable content that were not served by the cache during the current time period.

16.1.11.1 Metric Summary

The following table shows how often the metric's value is collected.

Target Version	Collection Frequency
All Versions	Every 5 Minutes

16.1.11.2 User Action

If the number of misses is high, then perform the following:

Review the caching rules configuration in Oacle9iAS Web Cache Manager.
In the Popular Requests page in Oacle9iAS Web Cache Manager, select the Not Cached from the Filter Documents list to view the most frequent misses.

16.1.12 Network Errors Per Second

The number of error pages that the cache has served per second to Web browsers due to a network error while connecting, sending, or receiving a response from an origin server.

16.1.12.1 Metric Summary

Table 16-4 Metric Summary Table

Target Version	Evaluation and Collection Frequency	Upload Frequency	Operator	Default Warning Threshold	Default Critical Threshold	Consecutive Number of Occurrences Preceding Notification	Alert Text
All Versions	Every 5 Minutes	After Every 12 Samples	>	.5	1	2	The cache encountered %value% network errors per second

16.1.12.2 User Action

If the number of network errors is consistently high, then consider improving the network connection between the cache and origin server.

16.1.13 Noncacheable Misses (% of requests)

The percentage of requests for non-cacheable content that was not served by the cache.

16.1.13.1 Metric Summary

The following table shows how often the metric's value is collected.

Target Version	Collection Frequency
All Versions	Every 5 Minutes

16.1.13.2 User Action

If the number of hits is low, then perform the following:

Review the caching rules configuration in OracleAS Web Cache Manager.
In the Popular Requests page in OracleAS Web Cache Manager, select the Not Cached from the Filter Documents list to view the most frequent misses. In addition, view the Cache Reason for the most frequent requests that were not cached.

16.1.14 Open Connections

The number of incoming open connections to the OracleAS Web Cache server and outgoing open connections to the origin servers.

16.1.14.1 Metric Summary

The following table shows how often the metric's value is collected.

Target Version	Collection Frequency
All Versions	Every 5 Minutes

16.1.14.2 User Action

No user action necessary. This metric is intended for informational purposes only.

16.1.15 Partial Page Errors Per Second

The number of error pages that the cache has served per second to Web browsers due to an HTML fragment retrieval problem for a page that supports partial page caching. This number includes errors returned when an uncaught exception occurs in the cache during ESI parsing or when the default ESI fragment is served. A default ESI fragment is served when OracleAS Web Cache is unable to fetch the src specified in an <esi:include> tag.

16.1.15.1 Metric Summary

Table 16-5 Metric Summary Table

Target Version	Evaluation and Collection Frequency	Upload Frequency	Operator	Default Warning Threshold	Default Critical Threshold	Consecutive Number of Occurrences Preceding Notification	Alert Text
All Versions	Every 5 Minutes	After Every 12 Samples	>	.5	1	2	The cache encountered %value% partial page errors per second

16.1.15.2 User Action

If the number of partial-page errors is consistently high, then improve the origin server side code that generates the ESI pages to catch exceptions.

16.1.16 Refreshes (% of requests)

The percentage of requests that resulted in the cache refreshing content from the origin servers.

16.1.16.1 Metric Summary

The following table shows how often the metric's value is collected.

Target Version	Collection Frequency
All Versions	Every 5 Minutes

16.1.16.2 User Action

Specific to your site.

16.1.17 Requests Per Second

The average number of requests served by the cache per second during the current time period.

16.1.17.1 Metric Summary

The following table shows how often the metric's value is collected.

Target Version	Collection Frequency
All Versions	Every 5 Minutes

16.1.17.2 User Action

No user action necessary. This metric is intended for informational purposes only.

16.1.18 Site Busy Errors Per Second

The number of error pages that the cache has served per second to Web browsers when origin server capacity has been reached.

16.1.18.1 Metric Summary

Table 16-6 Metric Summary Table

Target Version	Evaluation and Collection Frequency	Upload Frequency	Operator	Default Warning Threshold	Default Critical Threshold	Consecutive Number of Occurrences Preceding Notification	Alert Text
All Versions	Every 5 Minutes	After Every 12 Samples	>	.5	1	2	The cache encountered %value% site busy errors per second

16.1.18.2 User Action

If the number of site-busy errors is consistently high, then increase the capacity of the origin servers in the Origin Server page or OracleAS Web Cache Manager.

16.1.19 Size of Cached Documents (MB)

The size, in megabytes, of the objects currently stored in the cache. For a cache cluster member, this number is an aggregate of the owned and on-demand objects.

16.1.19.1 Metric Summary

The following table shows how often the metric's value is collected.

Target Version	Collection Frequency
All Versions	Every 5 Minutes

16.1.19.2 User Action

No user action necessary. This metric is intended for informational purposes only.

16.1.20 Stale Hits (% of requests)

The percentage of requests resolved by expired or invalidated content in the cache.

16.1.20.1 Metric Summary

Table 16-7 Metric Summary Table

Target Version	Evaluation and Collection Frequency	Upload Frequency	Operator	Default Warning Threshold	Default Critical Threshold	Consecutive Number of Occurrences Preceding Notification	Alert Text
All Versions	Every 5 Minutes	After Every 12 Samples	>	70	80	2	%value%%% of hits were stale cache hits

16.1.20.2 User Action

If the percentage of stale hits is high, then ensure that expired or invalidated pages are updated from the origin server in a timely fashion. Check the network capacity between the OracleAS Web Cache computer and the origin server.

16.1.21 Total Errors Per Second

The average number of error pages that the cache has served per second to Web browsers during the current time period.

16.1.21.1 Metric Summary

The following table shows how often the metric's value is collected.

Target Version	Collection Frequency
All Versions	Every 5 Minutes

16.1.21.2 User Action

No user action necessary. This metric is intended for informational purposes only.

16.1.22 Up Since

The time at which the cache was started or restarted.

16.1.22.1 Metric Summary

The following table shows how often the metric's value is collected.

Target Version	Collection Frequency
All Versions	Every 5 Minutes

16.1.22.2 User Action

No user action necessary. This metric is intended for informational purposes only.

16.2 ESI Errors

These metric columns provide information about OracleAS Web Cache EdgeSide Includes.

16.2.1 ESI Exceptions Not Caught Per Second

The number of error pages that the cache has served per second to Web browsers due to Edge Side Include (ESI) exception errors. These error pages are typically the result of ESI syntax errors.

16.2.1.1 Metric Summary

The following table shows how often the metric's value is collected.

Target Version	Collection Frequency
9.0.4.x	Every 5 Minutes

16.2.1.2 User Action

If the number of exception errors is consistently high, then improve the origin server side code that generates the ESI pages to catch exceptions.

16.2.2 Times Default ESI Fragment Served Per Second

The number of default Edge Side Include (ESI) fragments that the cache has served per second to Web browsers. A default ESI fragment is served when when OracleAS Web Cache is unable to fetch the src specified in an <esi:include> tag and the alt attribute, onerror attribute, or the try |attempt |except block are either not present or fail.

16.2.2.1 Metric Summary

The following table shows how often the metric's value is collected.

Target Version	Collection Frequency
9.0.4.x	Every 5 Minutes

16.2.2.2 User Action

If the number of default ESI fragments is consistently high, then review the ESI code.

16.3 Resource Usage

These metric columns provide information about CPU and memory usage.

16.3.1 CPU Idle Time (%)

The percentage of system CPU time that is idle.

16.3.1.1 Metric Summary

The following table shows how often the metric's value is collected.

Target Version	Collection Frequency
All Versions	Every 5 Minutes

16.3.1.2 User Action

If the load is high, then consider upgrading the cache computer.

16.3.2 Free Memory (%)

The amount of free physical memory, in megabytes, for the system.

16.3.2.1 Metric Summary

The following table shows how often the metric's value is collected.

Target Version	Collection Frequency
9.0.2.x and 9.0.3.x	Every 5 Minutes

16.3.2.2 User Action

If the load is high, then consider upgrading the cache computer.

16.3.3 Free Memory (MB)

The amount of free physical memory, in megabytes, for the system.

16.3.3.1 Metric Summary

The following table shows how often the metric's value is collected.

Target Version	Collection Frequency
All Versions	Every 5 Minutes

16.3.3.2 User Action

If the load is high, then consider upgrading the cache computer.

16.3.4 Other CPU Usage (%)

The percentage of the CPU usage by applications other than OracleAS Web Cache.

16.3.4.1 Metric Summary

The following table shows how often the metric's value is collected.

Target Version	Collection Frequency
All Versions	Every 5 Minutes

16.3.4.2 User Action

If CPU usage is high, then consider upgrading the cache computer.

16.3.5 Other Memory Usage (%)

The percentage of physical memory used by applications other than OracleAS Web Cache.

16.3.5.1 Metric Summary

The following table shows how often the metric's value is collected.

Target Version	Collection Frequency
9.0.2.x and 9.0.3.x	Every 5 Minutes

16.3.5.2 User Action

If the load is high, then consider upgrading the cache computer.

16.3.6 Other Memory Usage (MB)

The physical memory usage, in megabytes, by applications other than OracleAS Web Cache.

16.3.6.1 Metric Summary

The following table shows how often the metric's value is collected.

Target Version	Collection Frequency
All Versions	Every 5 Minutes

16.3.6.2 User Action

If the load is high, then consider upgrading the cache computer.

16.3.7 Total Memory (MB)

The amount of physical memory, in megabytes, for the system.

16.3.7.1 Metric Summary

The following table shows how often the metric's value is collected.

Target Version	Collection Frequency
9.0.2.x and 9.0.3.x	Every 5 Minutes

16.3.7.2 User Action

If the load is high, then consider upgrading the cache computer.

16.3.8 Web Cache CPU Usage (%)

The percentage of the CPU that is being used for OracleAS Web Cache. As traffic increases, CPU utilization increases.

16.3.8.1 Metric Summary

Table 16-8 Metric Summary Table

Target Version	Evaluation and Collection Frequency	Upload Frequency	Operator	Default Warning Threshold	Default Critical Threshold	Consecutive Number of Occurrences Preceding Notification	Alert Text
All Versions	Every 5 Minutes	After Every 12 Samples	>	Not Defined	Not Defined	2	CPU Utilization is %value%%%

16.3.8.2 User Action

If the load is high, then consider upgrading the cache computer.

16.3.9 Web Cache Memory Usage (%)

The percentage of the physical memory used by OracleAS Web Cache.

16.3.9.1 Metric Summary

Table 16-9 Metric Summary Table

Target Version	Evaluation and Collection Frequency	Upload Frequency	Operator	Default Warning Threshold	Default Critical Threshold	Consecutive Number of Occurrences Preceding Notification	Alert Text
All Versions	Every 5 Minutes	After Every 12 Samples	>	80	90	2	Memory Utilization is %value%%%

16.3.9.2 User Action

If the load is high, then consider upgrading the cache computer.

16.3.10 Web Cache Memory Usage (MB)

The amount of physical memory, in megabytes, that is being used by OracleAS Web Cache.

16.3.10.1 Metric Summary

The following table shows how often the metric's value is collected.

Target Version	Collection Frequency
All Versions	Every 5 Minutes

16.3.10.2 User Action

If the load is high, then consider upgrading the cache computer.

16.4 Response

This category indicates whether the OracleAS Web Cache instance is up and running or down and unavailable.

16.4.1 Status

This metric indicates whether the OracleAS Web Cache instance is up and running or down and unavailable.

16.4.1.1 Metric Summary

Table 16-10 Metric Summary Table

Target Version	Evaluation and Collection Frequency	Upload Frequency	Operator	Default Warning Threshold	Default Critical Threshold	Consecutive Number of Occurrences Preceding Notification	Alert Text
9.0.4.x	Every Minute	After Every 60 Samples	=	Not Defined	0	1	The Webcache instance is down

16.4.1.2 User Action

Specific to your site.

16.5 Server Performance

The columns in this metric provide information about the performance of origin server.

16.5.1 Active Requests

The current number of open connections that the cache has open to the origin server per second.

16.5.1.1 Metric Summary

The following table shows how often the metric's value is collected.

Target Version	Collection Frequency
All Versions	Every 5 Minutes

16.5.1.2 User Action

If the number is close to the connection limit, then set a larger capacity for the origin server in the Origin Servers page of OracleAS Web Cache Manager.

16.5.2 Processing Time (seconds)

The average number of seconds used to process a request during the current time period.

16.5.2.1 Metric Summary

The following table shows how often the metric's value is collected.

Target Version	Collection Frequency
All Versions	Every 5 Minutes

16.5.2.2 User Action

If the number is low, then improve the connection between the cache and origin server, or upgrade the origin server computer.

16.5.3 Proxy Server

Specifies whether or not the origin server is a proxy server. YES specifies that the origin server is a proxy server. NO specifies that the origin server is an application Web sever.

16.5.3.1 Metric Summary

The following table shows how often the metric's value is collected.

Target Version	Collection Frequency
All Versions	Every 5 Minutes

16.5.3.2 User Action

No user action necessary. This metric is intended for informational purposes only.

16.5.4 Requests Per Second

The average number of requests served per second during the current time period.

16.5.4.1 Metric Summary

The following table shows how often the metric's value is collected.

Target Version	Collection Frequency
All Versions	Every 5 Minutes

16.5.4.2 User Action

If this number is high, then increase the capacity of this origin server in the Origin Servers page of OracleAS Web Cache Manager, or load balance the requests among cache cluster members.

16.5.5 Status

The current status of the origin server. An up status specifies that the last communication with the origin server was successful. A down status specifies that the origin server is down. If this is the last origin server in a single or multiple server configuration, OracleAS Web Cache continues to forward requests to the origin server. If this is not the last server, then no new requests will be sent to origin server. However, OracleAS Web Cache will poll the inactive origin server until it is back online.

16.5.5.1 Metric Summary

The following table shows how often the metric's value is collected.

Target Version	Collection Frequency
All Versions	Every 5 Minutes

16.5.5.2 User Action

No user action necessary. This metric is intended for informational purposes only.