Product Documentation

Displaying Cached Objects and Cache Statistics

Oct 19, 2016

You can view particular cached objects, and you can view summary statistics on cache hits, misses, and memory usage. The statistics provide insight on the amount of data that is being served from the cache, what items are responsible for the largest performance benefit, and what you can tune to improve cache performance.

This section includes the following details:
  • Viewing Cached Objects
  • Finding Particular Cached Responses
  • Viewing Cache Statistics

Viewing Cached Objects

Updated: 2014-08-04

After enabling caching, you can view details for cached objects. For example, you can view the following items:

  • Response sizes and header sizes
  • Status codes
  • Content groups
  • ETag, Last-Modified, and Cache-Control headers
  • Request URLs
  • Hit parameters
  • Destination IP addresses
  • Request and response times

To view a list of cached objects by using the command line interface

At the command prompt, type:

show cache object
Table 1. Properties of Cached Objects

Properties

Specifies

Response size (bytes)

The size of the response header and body.

Response header size (bytes)

The size of the header portion of the response.

Response status code

The status code sent with the response.

ETag

The ETag header inserted in the response. Typically, this header indicates whether the response has changed recently.

Last-Modified

The Last-Modified header inserted in the response. This header indicates the date that the response was last changed.

Cache-Control

The Cache-Control header inserted in the response.

Date

The Date header that indicates when the response was sent.

Contentgroup

The content group where the response is stored.

Complex match

If this object was cached on the basis of parameterized values, this field value is YES.

Host

The host specified in the URL that requested this response.

Host port

The listen port for the host specified in the URL that requested this response.

URL

The URL issued for the stored response.

Destination IP

The IP address of the server from which this response was fetched.

Destination port

The listen port for the destination server.

Hit parameters

If the content group that stores the response uses hit parameters, they are listed in this field.

Hit selector

If this content group uses a hit selector, it is listed in this field.

Inval selector

If this content group uses an invalidation selector, it is listed in this field.

Selector Expressions

If this content group uses a selector, this field displays the expression that defines the selection rule.

Request time

The time in milliseconds since the request was issued.

Response time

The time in milliseconds since the cache started to receive the response.

Age

Amount of time the object has been in the cache.

Expiry

Amount of time after which the object is marked as expired.

Flushed

Whether the response has been flushed after expiry.

Prefetch

If Prefetch has been configured for this content group, the amount of time before expiry during which the object is fetched from the origin. Prefetch does not apply to negative objects (for example, 404 "object not found" responses).

Current readers

Approximately the current number of hits being served. When a response with a Content-Length header object is being downloaded, the current misses and the current readers values are each typically 1. When a chunked response object is being downloaded, the current misses value is typically 1, but the current readers value is typically 0, because the chunked response that is served to the client does not come from the integrated caching buffers.

Current misses

The current number of requests that resulted in a cache miss and fetching from the origin server. This value is typically 0 or 1. If Poll Every Time is enabled for a content group, the count can be greater than 1.

Hits

The number of cache hits for this object.

Misses

The number of cache misses for this object.

Compression format

The type of compression applied to this object. Compression formats include gzip, deflate, compress, and pack200-gzip.

HTTP version in response

The version of HTTP that was used to send the response.

Weak etag present in response

Strong etag headers change if the bits of an entity change. Strong headers are based on the octet values of an object. Weak etag headers change if the meaning of an entity changes. Weak etag values are based on semantic identity. Weak etags values start with a "W."

Negative marker cell

A marker object is cacheable, but it does not yet meet all the criteria for being cached. For example, the object may exceed the maximum response size for the content group. A marker cell is created for objects of this type. The next time a user sends a request for this object, a cache miss is served.

Reason marker created

The reason a marker cell was created (for example, “Waiting for minhit,” “Content-length response data is not in group size limit”).

Auto poll every time

If the integrated cache receives an already expired 200 OK response with validators (either the Last-Modified or the ETag response headers) it stores the response and marks it as Auto-PET (automatically poll every time).

NetScaler Etag inserted in response

A variation of the ETag header generated by the NetScaler appliance. A value of YES appears if the NetScaler inserts an Etag in the response.

Full response present in cache

Indicates whether this is a complete response.

Destination IP verified by DNS

Indicates whether DNS resolution was performed when storing the object.

Object stored through a cache forward proxy

Indicates whether this response was stored due to a forward proxy that is configured in the integrated cache.

Object is a Delta basefile

A response that is delta-compressed.

Waiting for minhits

Indicates whether this content group requires a minimum number of origin server hits before caching a response.

Minhit count

If this content group requires a minimum number of origin server hits before caching an object, this field displays a count of the number of hits received so far.

HTTP Request Method

The method, GET or POST, used in the request that obtained this object.

Stored by policy

The name of the caching policy that caused this object to be stored. A value of NOT AVAILABLE indicates that the policy has been deactivated or deleted. A value of NONE indicates that the object did not match a visible policy, but was stored according to internal criteria for caching.

Application firewall metadata exists

This parameter is used when the application firewall and the integrated cache are both enabled. The application firewall analyzes the contents of a response page, stores its metadata (for example, URLs and forms contained in page), and exports the metadata with the response to the cache. The cache stores the page and the metadata, and when the cache serves the page, it sends the metadata back to the request’s session.

HTTP callout object, name, type, response

These cells indicate whether this data was stored as a result of an HTTP Callout expression, and provide information about various aspects of the callout and the corresponding response. For more information about HTTP callouts, see "HTTP Callouts".

To view cached objects by using the configuration utility

Navigate to Optimization > Integrated Caching > Cache Objects. You can view all the cached objects and sort them accordingly as per your requirement.

Finding Particular Cached Responses

Updated: 2014-08-08

You can find individual items in the cache based on search criteria. There are different methods for finding cached items, depending on whether the content group that contains the data uses hit and invalidation selectors, as follows:

  • If the content group uses selectors, you can only conduct the search using the Locator ID for the cached item.
  • If the content group does not use selectors, you conduct the search using criteria such as URL, host, content group name, and so on.

When searching for a cached response, you can locate some items by URL and host. If the response is in a content group that uses a selector, you can find it only by using a Locator number (for example, 0x00000000ad7af00000050). To save a Locator number for later use, right-click the entry and select Copy. For more information about selectors, see "Configuring Selectors and Basic Content Groups."

To display cached responses in content groups that do not have a selector by using the command line interface

At the command prompt, type:

show cache object [-locator <positiveInteger>] | [(-url <URL> (-host <hostName> [-port <port>] [-groupName <contentGroupName>] [-httpMethod GET | POST ])) | [-httpStatus<positive integer>] | -group <contentGroupName> | -ignoreMarkerObjects (ON | OFF) | -includeNotReadyObjects (ON | OFF)]

To display cached responses in content groups that have a selector by using the command line interface

At the command prompt, type:

show cache object -locator <locatorString> MarkerObjects ( ON | OFF ) | -includeNotReadyObjects ( ON | OFF ) | [-httpStatus<positive integer>]

To display cached responses in content groups that do not have a selector by using the configuration utility

Navigate to Optimization > Integrated Caching > Cache Objects, click Search, and set the search criteria to view the required cached response.

If you have not yet configured any content groups, all of the objects are in the Default group.

To display cached responses in content groups that have a selector by using the configuration utility

Navigate to Optimization > Integrated Caching > Cache Objects, click Search, and set the selector search criteria to view the required cached response.

Viewing Cache Statistics

Updated: 2013-10-28

The following table summarizes the detailed cache statistics that you can view.

Table 2. Integrated Cache Statistics

Counter

Specifies

Hits

Responses that are found in and served from the integrated cache. Includes static objects such as image files, pages with status codes 200, 203, 300, 301, 302, 304, 307, 403, 404, 410, and responses that match a user-defined policy with a CACHE action..

Misses

Intercepted HTTP requests where the response was ultimately fetched from origin server.

Requests

Total cache hits plus total cache misses.

Non-304 hits

If the user requests an item more than once, and the item in the cache is unchanged since the last time the NetScaler appliance served it, the NetScaler appliance serves a 304 response instead of the cached object.

This statistic indicates how many items the NetScaler appliance served from the cache, excluding 304 responses.

304 hits

Number of 304 (object not modified) responses the NetScaler appliance served from the cache.

304 hit ratio (%)

Percentage of 304 responses that the NetScaler appliance served, relative to other responses.

Hit ratio (%)

Percentage of responses that the NetScaler appliance served from the cache (cache hits) relative to responses that could not be served from the cache.

Origin bandwidth saved (%)

An estimate of the processing capacity that the NetScaler appliance saved on the origin server due to serving responses from the cache.

Bytes served by the NetScaler

Total number of bytes that the NetScaler appliance served from the origin server and the cache.

Bytes served by cache

Total number of bytes that the NetScaler appliance served from the cache.

Byte hit ratio(%)

Percentage of data that the NetScaler appliance served from the cache, relative to all of the data in all served responses.

Compressed bytes from cache

Amount of data, in bytes, that the NetScaler appliance served in compressed form.

Storable misses

If the NetScaler appliance does not find a requested object in the cache, it fetches the object from the origin server. This is known as a cache miss. A storable cache miss can be stored in the cache.

Non-storable misses

A non-storable cache miss cannot be stored in the cache.

Misses

All cache misses.

Revalidations

Max-Age setting in a Cache-Control header determines, in number of seconds, when an intervening cache must revalidate the content with the integrated cache before serving it to the user.

For more information, see "Inserting a Cache-Control Header."

Successful revalidations

Number of re-validations that have been performed.

For more information, see "Inserting a Cache-Control Header."

Conversions to conditional req

A user-agent request for a cached PET object is always converted to a conditional request and sent to the origin server.

For more information, see "Polling the Origin Server Every Time a Request Is Received."

Storable miss ratio (%)

Storable cache misses as a percentage of non-storable cache misses.

Successful reval ratio (%)

Successful revalidations as a percentage of all revalidation attempts.

For more information, see "Inserting a Cache-Control Header."

Expire at last byte

Number of times that the cache expired content immediately after receiving the last body byte. Only applicable to positive responses, as described in the table "Cache Hits and Misses."

For more information, see "Example of Performance Optimization."

Flashcache misses

If you enable Flash Cache, the cache allows only one request to reach the server, eliminating flash crowds. This statistic indicates the number of Flash Cache requests that were cache misses.

For more information, "Queuing Requests to the Cache."

Flashcache hits

Number of Flash Cache requests that were cache hits.

For more information, see "Queuing Requests to the Cache."

Parameterized inval requests

Requests that match a policy with an invalidation (INVAL) action and a content group that uses an invalidation selector or parameters to selectively expire cached objects in the group.

Full inval requests

Requests that match an invalidation policy where the invalGroups parameter is configured and expires one or more content groups.

Inval requests

Requests that match an invalidation policy and result in expiration of specific cached responses or entire content groups.

Parameterized requests

Number of cache requests that were processed using a policy with a parameterized content group.

Parameterized non-304 hits

Number of cache requests that were processed using a policy with a parameterized content group, where full cached response was found, and the response was not a 304 (object not updated) response.

Parameterized 304 hits

Number of cache requests that were processed using a policy with a parameterized content group, where the cached object was found, and the object was a 304 (object not updated) response.

Total parameterized hits

Number of cache requests that were processed using a policy with a parameterized content group, where the cached object was found.

Parameterized 304 hit ratio (%)

Percentage of 304 (object not updated) responses that were found using a parameterized policy, relative to all cache hits.

Poll every time requests

If Poll Every Time is enabled, the NetScaler appliance always consults the origin server before serving a stored object.

For more information, see "Polling the Origin Server Every Time a Request Is Received."

Poll every time hits

Number of times a cache hit was found using the Poll Every Time method.

For more information, see "Polling the Origin Server Every Time a Request Is Received."

Poll every time hit ratio (%)

Percentage of cache hits using the Poll Every Time method, relative to all searches for cached objects using Poll Every Time.

For more information, see "Polling the Origin Server Every Time a Request Is Received."

Maximum memory (KB)

Maximum amount of memory in the NetScaler appliance that is allocated to the cache. For more information, see "Configuring Global Attributes for Caching."

Maximum memory active value (KB)

Maximum amount of memory (active value) that will be set after the memory is actually allocated to the cache. For more information, see "How to Configure the Integrated Caching Feature of a NetScaler Appliance for various Scenarios."

Utilized memory (KB)

Amount of memory that is actually being used.

Memory allocation failures

Number of failed attempts to utilize memory for the purpose of storing a response in the cache.

Largest response so far

Largest response in bytes found in either the cache or the origin server and sent to the client.

Cached objects

Number of objects in the cache, including responses that have not yet been fully downloaded and responses that have been expired but not yet flushed.

Marker objects

Marker objects are created when a response exceeds the maximum or minimum response size for the content group, or has not yet received the minimum number of hits for the content group.

Hits being served

Number of hits that have been served from the cache.

Misses being handled

Responses that were fetched from the origin server, stored in the cache, and then served. Should approximate the number for storable misses. Does not include non-storable misses.

To view summary cache statistics by using the command line interface

At the command prompt, type:

stat cache

To view specific cache statistics by using the command line interface

At the command prompt, type:

stat cache -detail
Viewing stat cache detail 복사

> stat cache -detail

Integrated Cache Statistics - Detail

Integrated Cache Statistics - Summary

                                          Rate (/s)                Total

Hits                                               0                    0

Misses                                             0                    0

Requests                                           0                    0

Hit ratio(%)                                      --                    0

Origin bandwidth saved(%)                         --                    0

Cached objects                                    --                    0

Marker objects                                    --                    0

                                          Rate (/s)                Total

Requests                                           0                    0

 

Hit Statistics

                                          Rate (/s)                Total

Non-304 hits                                       0                    0

304 hits                                           0                    0

Sql hits                                           0                    0

Hits                                               0                    0

304 hit ratio(%)                                  --                    0

Hit ratio(%)                                      --                    0

Origin bandwidth saved(%)                         --                    0

 

Byte Statistics

                                          Rate (/s)                Total

Bytes served by NetScaler                        648             55379204

Bytes served by cache                              0                    0

Byte hit ratio(%)                                 --                    0

Compressed bytes from cache                        0                    0

 

Miss Statistics

                                          Rate (/s)                Total

Storable misses                                    0                    0

Non-storable misses                                0                    0

Misses                                             0                    0

Revalidations                                      0                    0

Successful revalidations                           0                    0

Conversions to conditional req                     0                    0

Storable miss ratio(%)                            --                    0

Successful reval ratio(%)                         --                    0

 

Flashcache Statistics

                                          Rate (/s)                Total

Expire at last byte                                0                    0

Flashcache misses                                  0                    0

Flashcache hits                                    0                    0

 

Invalidation Statistics

                                          Rate (/s)                Total

Parameterized inval requests                       0                    0

Full inval requests                                0                    0

Inval requests                                     0                    0

 

Parameterized Caching Statistics

                                          Rate (/s)                Total

Parameterized requests                             0                    0

Parameterized non-304 hits                         0                    0

Parameterized 304 hits                             0                    0

Total parameterized hits                           0                    0

Parameterized 304 hit ratio(%)                    --                    0

 

Poll Every Time (PET) Statistics

                                          Rate (/s)                Total

Poll every time requests                           0                    0

Poll every time hits                               0                    0

Poll every time hit ratio(%)                      --                    0

 

Memory Usage Statistics

                                              Total

Maximum memory(KB)                                 0

Maximum memory active value(KB)                    0

Utilized memory(KB)                                0

Memory allocation failures                         0

Largest response so far(B)                         0

Cached objects                                     0

Marker objects                                     0

 

Hits being served                                  0

Misses being handled                               0

 Done

 

To view summary cache statistics by using the configuration utility

  1. Click the Dashboard tab at the top of the page.
  2. Scroll down to the Integrated Caching section of the window.
  3. To see detailed statistics, click the More... link at the bottom of the table.

To view specific cache statistics by using the configuration utility

  1. Click the Reporting tab at the top of the page.
  2. Under Built-In Reports, expand Integrated Cache, and then click the report with the statistics you want to view.
  3. To save the report as a template, click Save As and name the report. The saved report appears underCustom Reports.