NAME

       fs_bypassthreshold - get/set Cache Bypass file size threshold

SYNOPSIS

       fs bypassthreshold [-size <file size>] [-help]

       fs bypassthresh [-s <file size>] [-h]

DESCRIPTION

       The fs bypassthreshold command either changes the AFS client Cache Bypass file size
       threshold, or reports the current threshold. Normally, when an application tries to read
       data via the OpenAFS client, the client will fetch the required data from the fileserver,
       store the results in the local cache, and then serve the application request from the
       local cache. When the Cache Bypass feature is enabled, certain files will be read directly
       from the network, and the data will not be saved to the local cache. In some scenarios,
       this can provide a significant performance improvement, especially if the data is only
       read once.

       Currently, the only way to specify which files should bypass the cache and which files
       should not, is by file size. In the future, different mechanisms may exist for specifying
       which files should bypass the local cache and which should not.

       If -size is not specified, fs bypassthreshold just reports the current threshold and
       exits.

CAUTIONS

       Cache Bypass is still considered an experimental feature. Even in stable releases of
       OpenAFS, it is not considered as stable as the rest of OpenAFS.

OPTIONS

       -size <file size>
           Specifies how large a file must be in order to enable Cache Bypass mode.  If a file is
           larger than the specified file size (in bytes), reading from that file will bypass the
           local cache and be read directly from the network. A file size of -1 indicates that
           Cache Bypass should be disabled complete, so no files will enable Cache Bypass mode,
           no matter how large they are.

           By default, Cache Bypass is disabled.

       -help
           Prints the online help for this command. All other valid options are ignored.

OUTPUT

       The output format is identical whether or not -size was specified. If -size is specified,
       the bypass threshold is changed, and the output represents the new, changed, threshold.
       Otherwise the output represents the current threshold.

EXAMPLES

       The following example turns on Cache Bypass with a threshold of 4KiB:

          % fs bypassthreshold 4096
          Cache bypass threshold 4096

       The following example disables Cache Bypass:

          % fs bypassthreshold -1
          Cache bypass threshold -1 (disabled)

       The following example examines the current Cache Bypass threshold:

          % fs bypassthreshold
          Cache bypass threshold 4096

PRIVILEGE REQUIRED

       To set the bypass threshold, the issuer must be logged in as the local superuser "root".
       Otherwise, no privilege is required.

COPYRIGHT

       Copyright 2012 Sine Nomine Associates

       This documentation is covered by the BSD License as written in the doc/LICENSE file. This
       man page was written by Andrew Deason for OpenAFS.