Provided by: cachefilesd_0.9-3.1_amd64 bug

NAME

       /etc/cachefilesd.conf - Local file caching configuration file

SYNOPSIS

       The  configuration  file for cachefilesd which can manage a persistent cache for a variety
       of network filesystems using a set of files on an already mounted filesystem as  the  data
       store.

DESCRIPTION

       This  configuration  file  can  contain  a  number  of  commands.  Each one should be on a
       separate line.  Blank lines and lines beginning with a '#' character are considered to  be
       comments and are discarded.

       The only mandatory command is:

       dir <path>
              This command specifies the directory containing the root of the cache.  It may only
              specified once per configuration file.

       All the other commands are optional:

       brun <N>%

       bcull <N>%

       bstop <N>%

       frun <N>%

       fcull <N>%

       fstop <N>%
              These commands configure the culling limits.  The defaults are 7% (run), 5%  (cull)
              and 1% (stop) respectively.  See the section on cache culling for more information.

              The  commands  beginning  with a 'b' are file space (block) limits, those beginning
              with an 'f' are file count limits.

       tag <name>
              This command specifies a tag to FS-Cache to use in distinguishing multiple  caches.
              This  is  only required if more than one cache is going to be used.  The default is
              "CacheFiles".

       culltable <log2size>
              This command specifies the size of the tables holding the lists of cullable objects
              in the cache.  The bigger the number, the faster and more smoothly that culling can
              proceed when there are many objects in the cache,  but  the  more  memory  will  be
              consumed by cachefilesd.

              The  quantity  is  specified  as log2 of the size actually required, for example 12
              indicates a table of 4096 entries and 13 indicates 8192 entries.   The  permissible
              values  are  between 12 and 20, the latter indicating 1048576 entries.  The default
              is 12.

       debug <mask>
              This command specifies a numeric bitmask to control debugging in the kernel module.
              The  default  is zero (all off).  The following values can be OR'd into the mask to
              collect various information:

              1      Turn on trace of function entry (_enter() macros)

              2      Turn on trace of function exit (_leave() macros)

              4      Turn on trace of internal debug points (_debug())

              This mask can also be set through /sys/module/cachefiles/parameters/debug.

EXAMPLES

       As an example, consider the following:

              dir /var/fscache
              tag mycache
              brun 10%
              bcull 7%
              bstop 3%

       The places the cache storage objects in a directory called "/var/fscache", names the cache
       "mycache",  permits  the cache to run freely as long as there's at least 10% free space on
       /var/fscache/, starts culling the cache when the free  space  drops  below  7%  and  stops
       writing new stuff into the cache if the amount of free space drops below 3%.  If the cache
       is suspended, it won't reactivate until the amount of free space rises  again  to  10%  or
       better.

CACHE CULLING

       The  cache  may need culling occasionally to make space.  This involves discarding objects
       from the cache that have been used less recently than anything else.  Culling is based  on
       the access time of data objects.  Empty directories are culled if not in use.

       Cache culling is done on the basis of the percentage of blocks and the percentage of files
       available in the underlying filesystem.  There are six "limits":

       brun

       frun   If the amount of free space and the number of available files in  the  cache  rises
              above both these limits, then culling is turned off.

       bcull

       fcull  If  the  amount  of  available  space or the number of available files in the cache
              falls below either of these limits, then culling is started.

       bstop

       fstop  If the amount of available space or the number of  available  files  in  the  cache
              falls  below  either  of  these limits, then no further allocation of disk space or
              files is permitted until culling has raised things above these limits again.

       These must be configured thusly:

              0 <= bstop < bcull < brun < 100
              0 <= fstop < fcull < frun < 100

       Note that these are percentages of available space and available files, and do not  appear
       as 100 minus the percentage displayed by the df program.

       The  userspace  daemon scans the cache to build up a table of cullable objects.  These are
       then culled in least recently used order.  A new scan of the cache is started as  soon  as
       space  is  made  in the table.  Objects will be skipped if their atimes have changed or if
       the kernel module says it is still using them.

SEE ALSO

       cachefilesd(8), df(1), /usr/share/doc/cachefilesd-*/README

AUTHORS

       The cachefilesd software has been developed by David Howells