1CACHEFILESD.CONF(5)          Cache Files Utilities         CACHEFILESD.CONF(5)
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NAME

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

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

14       This  configuration  file  can  contain a number of commands.  Each one
15       should be on a separate line.  Blank lines and lines beginning  with  a
16       '#' character are considered to be comments and are discarded.
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18       The only mandatory command is:
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20       dir <path>
21              This  command specifies the directory containing the root of the
22              cache.
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24       All the other commands are optional:
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26       brun <N>%
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28       bcull <N>%
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30       bstop <N>%
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32       frun <N>%
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34       fcull <N>%
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36       fstop <N>%
37              These commands configure the culling limits.  The  defaults  are
38              7% (run), 5% (cull) and 1% (stop) respectively.  See the section
39              on cache culling for more information.
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41              The commands beginning with a 'b' are file space (block) limits,
42              those beginning with an 'f' are file count limits.
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44       tag <name>
45              This  command specifies a tag to FS-Cache to use in distinguish‐
46              ing multiple caches.  This is only required  if  more  than  one
47              cache is going to be used.  The default is "CacheFiles".
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49       debug <mask>
50              This command specifies a numeric bitmask to control debugging in
51              the kernel module.  The default is zero (all off).  The  follow‐
52              ing values can be OR'd into the mask to collect various informa‐
53              tion:
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55              1      Turn on trace of function entry (_enter() macros)
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57              2      Turn on trace of function exit (_leave() macros)
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59              4      Turn on trace of internal debug points (_debug())
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61              This mask can also be set through /proc/sys/fs/cachefiles/debug.
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EXAMPLES

64       As an example, consider the following:
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66              dir /var/fscache
67              tag mycache
68              brun 10%
69              bcull 7%
70              bstop 3%
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72       The  places  the  cache  storage  objects   in   a   directory   called
73       "/var/fscache",  names  the  cache  "mycache", permits the cache to run
74       freely as long as there's at least 10%  free  space  on  /var/fscache/,
75       starts  culling  the cache when the free space drops below 7% and stops
76       writing new stuff into the cache if the  amount  of  free  space  drops
77       below  3%.   If  the  cache is suspended, it won't reactivate until the
78       amount of free space rises again to 10% or better.
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CACHE CULLING

81       The cache may need culling occasionally to make space.   This  involves
82       discarding  objects  from  the  cache that have been used less recently
83       than anything else.  Culling is  based  on  the  access  time  of  data
84       objects.  Empty directories are culled if not in use.
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86       Cache  culling is done on the basis of the percentage of blocks and the
87       percentage of files available in the underlying filesystem.  There  are
88       six "limits":
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90       brun
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92       frun   If the amount of free space and the number of available files in
93              the cache rises above both these limits, then culling is  turned
94              off.
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96       bcull
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98       fcull  If  the  amount  of  available  space or the number of available
99              files in the cache falls below  either  of  these  limits,  then
100              culling is started.
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102       bstop
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104       fstop  If  the  amount  of  available  space or the number of available
105              files in the cache falls below either of these limits,  then  no
106              further  allocation  of  disk  space or files is permitted until
107              culling has raised things above these limits again.
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109       These must be configured thusly:
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111              0 <= bstop < bcull < brun < 100
112              0 <= fstop < fcull < frun < 100
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114       Note that these are percentages of available space and available files,
115       and  do not appear as 100 minus the percentage displayed by the df pro‐
116       gram.
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118       The userspace daemon scans the cache to build up a  table  of  cullable
119       objects.   These  are  then culled in least recently used order.  A new
120       scan of the cache is started as soon as space is  made  in  the  table.
121       Objects  will  be skipped if their atimes have changed or if the kernel
122       module says it is still using them.
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SEE ALSO

125       cachefilesd(8), df(1), /usr/share/docs/cachefilesd-*/README
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AUTHORS

128       The cachefilesd software has been developed by David Howells
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132Linux                            11 July 2005              CACHEFILESD.CONF(5)
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