16 Web Cache

This chapter describes Oracle Web Cache metrics.

Performance by Web Cache Instance

Provides information about the performance metrics for the Web Cache instance.

Instance

This category provides performance-request metrics for the cache.

Request Processing Time (milli seconds)

This metric specifies the average number of seconds used to process a request during the current time period.

User Action

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

Request Throughput (per second)

This metric specifies the average number of requests served for each second during the current time period.

User Action

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

Resource Usage

This category of metrics shows the resource usage of the computer with Oracle Web Cache.

CPU Usage (%)

This metric specifies the percentage of the CPU that is being used for Oracle Web Cache. As traffic increases, CPU utilization increases.

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.

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 3 Samples	>	Not Defined	Not Defined	2	CPU Utilization is %value%%%

User Action

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

CPU Idle Time (%)

This metric specifies the percentage of system CPU time that is idle.

Metric Summary

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

Target Version	Collection Frequency
All Versions	Every 5 Minutes

User Action

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

Other CPU Usage (%)

The percentage of physical memory usage by applications other than Oracle Web Cache.

Metric Summary

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

Target Version	Collection Frequency
All Versions	Every 5 Minutes

User Action

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

Memory Usage (MB)

This metric specifies the total memory used by Oracle Web Cache.

Metric Summary

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

Target Version	Collection Frequency
All Versions	Every 5 Minutes

User Action

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

Free Memory (MB)

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

Metric Summary

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

Target Version	Collection Frequency
All Versions	Every 5 Minutes

Other Memory Usage (MB)

Metric Summary

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

Target Version	Collection Frequency
All Versions	Every 5 Minutes

Total Memory (MB)

This metric shows the total memory of the host that has Oracle Web Cache.

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

Memory Usage (%)

This metric specifies the percentage of total memory that is being utilized for cache memory.

Metric Summary

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 3 Samples	>	80	90	2	Memory Utilization is %value%%%

Free Memory (%)

This metric specifies the percentage of total memory that is being utilized for cache memory.

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

Other Memory Usage (%)

Percent of memory used by processes other than Oracle Web Cache.

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

Start Time (ms since Epoch)

This metric shows the start time of Oracle Web Cache.

Up Time (ms since Epoch)

This metric shows the total time the Oracle Web Cache has been running.

Response

This category shows the availability of the cache server process, which manages the cache.

Response Admin

This category shows the availability of the admin server process, which provides administrative access to the cache.

Admin Process Status

This metric indicates whether the admin server process for the Oracle Web Cache instance is up (1) or down (0). The admin server process provides administrative access to cache.

Metric Summary

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 Minute	After Every 60 Samples	=	Not Defined	0	1	The Oracle Web Cache admin server process is down

User Action

If the admin server process is down, the context pane for the configuration pages displays an error, indicating that configuration is unavailable because the admin server process is down. To start the admin server process, from the Web Cache menu, choose Control, then Start Up, Shut Down, or Restart. See Starting and Stopping Oracle Web Cache for more information about starting Oracle Web Cache.

Response - Status

This metric indicates whether the cache server process for the Oracle Web Cache instance is up (1) or down (0).

Metric Summary

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 Minute	After Every 60 Samples	=	Not Defined	0	1	The Oracle Web Cache cache server process is down

User Action

See Starting and Stopping Oracle Web Cache for more information about starting Oracle Web Cache.

Performance of each Site with Summary

This category provides performance metrics for each site.

Total Number of Bytes Saved by Compression

This metric specifies the accumulated number of bytes that would be sent to clients if in-cache compression is disabled.

User Action

If the number is low, then compression is not providing much benefit to the site. Try enabling compression in all caching rules to allow Oracle Web Cache to determine compressibility automatically based on the content type.

Cache Size

The metric specifies 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.

User Action

No action user required. As Oracle Web Cache only cleans up invalid or expired objects on demand when memory is needed, this number may remain at a large value.

Total Number Error Pages Served

The metric specifies the accumulated number of error pages that Oracle Web Cache served to Web browsers since the cache was started.

User Action

Oracle Web Cache serves error pages when there are problems fetching content from the origin server or when there ESI processing issues with the content. Even a small number can indicate an issue with site content or with origin server health.

Hit Rate (in %)

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

User Action

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

1. Review the caching rules configuration in the Caching Rules page.

2. In the Popular Requests page, select Non Cache Popular Requests from the Show Popular Requests list to view the most frequent misses.

3. In the results table, view the Caching Reason column for the most frequent URL requests that were not cached.

4. Configure caching rules to cache the popular requests. See Configure Caching Rules.

Number of Cached

This metric specifies the number of objects cached.

Currently Open connections

This metric specifies the current number of incoming open connections to the Oracle Web Cache server and outgoing open connections to the origin servers.

User Action

If the number is close to the origin server connection limit, then set a larger capacity for the origin server from the Origin Servers page.

Total Number of Requests Denied

This metric specifies the accumulated number of requests denied by request filters.

User Action

Any non-zero number may be an indication of an attack on the site or an issue with the configuration of request filters.

Total Number of Requests Served

This metric specifies the accumulate number of requests that Oracle Web Cache has served.

WebCache_nontimedHost

This category provides performance-request metrics for the origin servers. Please also review the metrics in the WebCache_timedHost category for additional metrics for origin servers.

Capacity.value

This informational metric specifies the capacity you specified in the Origin Servers page for this origin server.

Load.value

This metric specifies the current number of connections from Oracle Web Cache that the origin server has open.

MaxLoad.value

The metric specifies the maximum number of connections that the origin server has had open at one time.

Port.value

The information metric specifies the port number from which the origin server is listening for Oracle Web Cache requests.

WebCache_timedHost

This category provides performance-request metrics for the origin servers. Please also review the metrics in the WebCache_nontimedHost category for additional metrics for origin servers.

AvgLatency.value

This metric shows the average amount of time for client requests forwarded by Oracle Web Cache to be resolved.

User Action

If the latency appears high, then the administrator for the origin server or content source may need to add more system resources.

Latency.value

This metric shows the total time for client requests forwarded by Oracle Web Cache to be resolved, since the cache was started.

User Action

If the latency appears high, then the administrator for the origin server or content source may need to add more system resources.

Request.value

This metric specifies the accumulated number of client requests forwarded by Oracle Web Cache that the origin server has processed.

User Action

You can increase cache hit rate and lower the number client requests to the origin server by configuring caching rules for popular requests:

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

1. Review the caching rules configuration in the Caching Rules page.

2. In the Popular Requests page, select Non Cache Popular Requests from the Show Popular Requests list to view the most frequent misses.

3. In the results table, view the Caching Reason column for the most frequent URL requests that were not cached.

4. Configure caching rules to cache the popular requests. See Configure Caching Rules.

RequestFailure.value

This metric specifies the accumulated number of client requests forwarded by Oracle Web Cache that resulted in an error.