Table of Contents
- Introduction
- Installation
- Handling Challenger
- Virtual Servers
- Configuration Examples
- Modules
- Filesystems
- RXML Tags
- Graphics
- Proxy

  | · Introduction · HTTP Proxy · SSL Proxy · FTP Gateway · Disk Cache

- Databases
- Miscellaneous Modules
- Security Considerations
- Scripting
- Frontpage
- Upgrading
- Third Party Extensions
- Portability
- Reporting Bugs
- Appendix

Disk Cache
The disk cache subsystem of Challenger handles caching for proxy modules. Currently only the HTTP-Proxy module caches requests. The disk cache is enabled by setting the global variable Global Variables/Proxy disk cache.../Enabled variables to Yes.

It is the disk cache system that handles which requests are to be cached. Files in the disk cache are removed by a garbage collector process, that is run at specified intervals.

`Base Cache Dir`
  The directory where the disk cache should be kept.

`Bytes per second`
  How the garbage collector should treat file size. Each byte of file size will be equal to a certain number of seconds of age. This way, really large files will be treated as older files and removed before smaller files of the same age.

`Clean size`
  Minimum number of megabytes to remove per garbage collect.

`Garbage collector logfile`
  If set, a log file will be kept with information about removed and refreshed files, as well as cache and disk status.

`Keep without Content-Length`
  Keep files that have no Content-Length header. This will make the cache store more files, but it will also be possible that partially downloaded files, as well as dynamic pages, are cached.

`Last resort`
  How many days to keep files with no Expire or Last-Modified headers.

`Maximum number of files`
  Maximum number of files to be cached.

`Minimum available free space and inodes`
  What percentage of disk space and disk inodes must be available on the file system with the cache. By setting this variable, it is possible to make sure that the disk cache will never fill the entire file system.

`Number of hash directories`
  The number of directories the cache should consist of.

  If this variable is changed, it will no longer be possible to access the old cache.

`Refresh on Last-Modified`
  If set, the disk cache will use the Last-Modified header to determine how long a file should be cached, if the file doesn't contain any Expire header. The file will be kept until it has doubled it's age.

`Size`
  The maximum size of the cache, in megabytes.