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NAME

       cephfs - ceph file system options utility

SYNOPSIS

       cephfs [ path command options ]

DESCRIPTION

       cephfs  is  a control utility for accessing and manipulating file layout and location data
       in the Ceph distributed file system.

       Choose one of the following three commands:

       · show_layout View the layout information on a file or directory

       · set_layout Set the layout information on a file or directory

       · show_location View the location information on a file

OPTIONS

       Your  applicable  options  differ  depending  on  whether  you  are  setting  or   viewing
       layout/location.

   Viewing options:
       -l --offset
              Specify an offset for which to retrieve location data

   Setting options:
       -u --stripe_unit
              Set the size of each stripe

       -c --stripe_count
              Set the number of stripes per object

       -s --object_size
              Set the size of the objects to stripe across

       -p --pool
              Set the pool (by numeric value, not name!) to use

       -o --osd
              Set the preferred OSD to use as the primary

LIMITATIONS

       When  setting layout data, the specified stripe unit and stripe count must multiply to the
       size of an object. Any parameters  you  don't  set  explicitly  are  left  at  the  system
       defaults.

       Obviously setting the layout of a file and a directory means different things. Setting the
       layout of a file specifies exactly how to place the individual file.  This  must  be  done
       before  writing  any data to it. Truncating a file does not allow you to change the layout
       either.

       Setting the layout of a directory sets the "default layout", which is used to set the file
       layouts  on  any  files  subsequently  created  in  the  directory  (or any subdirectory).
       Pre-existing files do not have their layouts changed.

       You'll notice that the layout information allows  you  to  specify  a  preferred  OSD  for
       placement. This is allowed but is not recommended since it can dramatically unbalance your
       storage cluster's space utilization.

AVAILABILITY

       cephfs is part of the Ceph distributed file system. Please  refer  to  the  Ceph  wiki  at
       http://ceph.newdream.net/wiki for more information.

SEE ALSO

       ceph(8)

COPYRIGHT

       2011, New Dream Network