Configuring Cache Parameters

The following sections describe how to configure advanced cache parameters for Novell BorderManager 3.7:

• Configuring Cache Aging Parameters

  This section includes configuration of HTTP, FTP, and Gopher revalidation times.

• Configuring Cache Control Parameters

  This section includes configuration of maximum cached file size and whether Java* applets are stripped from HTML files.

• Configuring Cache Location Parameters

  This section includes configuration of the cache directory and volume.

• Configuring Cachable Object Control Parameters

  This section includes configuration of noncachable URL patterns.

Configuring Cache Aging Parameters

To configure cache aging parameters:

1. In NetWare Administrator, select the Novell BorderManager 3.7 Setup page for the server.

2. Select an HTTP or FTP proxy or acceleration service, then click Caching.

3. From the Cache Aging tab, specify the following HTTP cache aging values:

   • HTTP Maximum Revalidation Time---The maximum number of hours or days HTTP data is cached before it is revalidated with the origin Web server. This overrides the Time to Expire specified by the origin Web server if it is greater than this value.
   • HTTP Default Revalidation Time---The number of hours or minutes HTTP data is cached before it is revalidated with the origin Web server. The data is revalidated if the origin Web server does not specify the Time to Expire.
   • HTTP Minimum Revalidation Time---The minimum number of hours or minutes HTTP data is cached by the server. This overrides the Time to Expire specified by the origin Web server if the time specified is less than this value. This parameter does not override the No Cache or Must Revalidate directives from the origin Web server.
   • FTP Revalidation Time---The number of hours or days FTP data is cached before it is revalidated with the origin Web server.
   • Gopher Revalidation Time---The number of hours or days Gopher data is cached before it is revalidated with the origin Web server.
   • HTTP Failed Request Cache Time---The number of seconds or minutes after which HTTP will return a failure for the requested pages that the proxy server could not retrieve from the origin Web server.
   • Maximum Hot Unreferenced Time---How long a node (or page) stays hot, or in a state where it can be more quickly accessed by the browser again after it has accessed the node once. The default is 20 minutes, after which the node is closed and the information is removed from memory. It takes longer for the proxy to access a node in cold state.

     NOTE:  This parameter works in conjunction with the Maximum Number of Hot Nodes parameter on the Cache Control tab. Refer to Configuring Cache Parameters for more information.

4. Click OK, then click OK again from the Novell BorderManager 3.7 Setup page.

Configuring Cache Control Parameters

These parameters let you specify the maximum cached file size for each protocol, as well as the cache hash table size, number of hot nodes, and age ratio of the cache size to deleted files.

To configure cache control parameters:

1. In NetWare Administrator, select the Novell BorderManager 3.7 Setup page for the server.

2. Select an HTTP or FTP proxy or acceleration service, then click Caching.

3. From the Cache Control tab, specify the following:

   • Maximum size of the file that is cached for each URL protocol request type---Enter this value in megabytes. Any file larger than the specified size is not cached. The default is 30 MB.
   • Size of the cache hash table---The table is used by the proxy to locate a URL in its cache. Its size determines the speed of the information lookup. The default is 128,000 entries, or 51 KB of memory.

     NOTE:  Increasing the maximum number of hot nodes may enhance performance more than increasing the size of the cache hash table.

   • Maximum number of hot nodes or objects that can be cached---This is the number of nodes or pages that are hot, or in a state to be more quickly accessed by the browser again after it has accessed the node once. This parameter works in conjunction with the Maximum Hot Unreferenced Time parameter on the Cache Aging tab.

     NOTE:  The maximum number of hot nodes must always be less than the maximum number of open files in NetWare. If you increase the maximum number of hot nodes from the default, make sure you also increase the maximum number of open files, up to a maximum of 100,000.

   • Maximum age ratio of the cache size to deleted files---This value determines how much space on the volume is used for caching and how many deleted files remain on the volume.
   • Whether Read-ahead is enabled and whether the proxy should read ahead for embedded images or page links---Read-ahead signals the proxy to cache the data and examine the HTML page to locate all embedded objects, including images and links to other pages. When Read-ahead is enabled, the browser recognizes requests ahead of time.

4. Click OK > OK from the Novell BorderManager 3.7 Setup page.

Configuring Cache Location Parameters

You can specify a different location for the cache.

To configure cache location parameters:

1. In NetWare Administrator, select the Novell BorderManager 3.7 Setup page for the server.

2. Select an HTTP or FTP proxy or acceleration service > click Caching.

3. From the Cache Location tab, specify the following:

   • A server pathname as a cache storage directory---The default is \ETC\PROXY\CACHE. The volume name is optional. If you do not specify a volume name, the default SYS: is used.

     NOTE:  For improved stability and performance, we recommend that you set up a separate volume other than SYS: for the proxy cache directory, with compression and suballocation disabled, no long namespace support, and block size set to 16K.

   • (After clicking Add) A volume name to the Volume list---This specifies a different cache location. Be sure to include a colon at the end of the volume name.
   • The number of directories available per volume.

4. Click OK, then click OK again from the Novell BorderManager 3.7 Setup page.

5. Stop and restart the proxy server for the changes to take effect.

   The cache on the SYS: volume will not be moved to the new volume name.

Configuring Cachable Object Control Parameters

These parameters let you control which URL patterns are not cached, as well as what happens with objects that have a question mark (?) in the URL, /cgi in the pathname, or a no-cache reply header.

You can specify whether to cache URLs and objects with certain predefined patterns or access them directly without caching by the proxy server (be noncachable). When no caching is specified, the proxy server simply forwards the request from the server to the requesting client. Objects with a question mark (?) in the URL, /cgi in the pathname, or a no-cache reply header are not cached by default unless you specify otherwise.

To configure cachable object control parameters, complete the following steps:

1. In NetWare Administrator, select the Novell BorderManager 3.7 Setup page for the server.

2. Select an HTTP or FTP proxy or acceleration service, then click Caching.

3. Click the Cachable Object Control tab.

4. Click Add to specify a list of URL patterns that will not be cached.

   1. Specify the following information:

      • Scheme---Specify a scheme type of HTTP, FTP, Gopher, or HTTPS.
      • Hostname---Specify any hostname or enter a specific hostname that must be matched. You can also check the check box to match any hostname that ends with the specified domain.
      • Port---Specify any port number or enter a specific port number.
      • Path---Specify any path or enter a specific pathname. You can also check the check box to match any path that begins with the specified name.
      • Extension---Specify any extension or enter a specific extension.

   2. Click OK.

   NOTE:  If you specify a long list of patterns, the proxy server performance will be affected.

5. Specify the actions taken for the following objects:

   • Objects with a question mark (?) in their URL
   • Objects with /cgi in their paths
   • Objects with a no-cache reply header

   These objects are not cached by default. Specify to cache these objects if you are setting up an accelerator. Or you can specify to not cache and send replies to all browsers that request the information at the same time. This reduces how often the proxy must retrieve information from the origin Web server. Specify to not cache or split requests that have a cookie to avoid sending different replies to different users for the same request.

6. Click OK, then click OK again from the Novell BorderManager 3.7 Setup page.