cephfs - ceph file system options utility
cephfs [ path command options ]
is a control utility for accessing and manipulating file layout
and location data in the Ceph distributed storage system.
Choose one of the following three commands:
- show_layout View the layout information on a file or
- set_layout Set the layout information on a file or
- show_location View the location information on a
Your applicable options differ depending on whether you are setting or viewing
- -l --offset
- Specify an offset for which to retrieve location data
- -u --stripe_unit
- Set the size of each stripe
- -c --stripe_count
- Set the number of objects to stripe across
- -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 (deprecated and
When setting layout data, the specified object size must evenly divide by the
specified stripe unit. Any parameters you don't set explicitly are left at the
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
You'll notice that the layout information allows you to specify a preferred OSD
for placement. This feature is unsupported and ignored in modern versions of
the Ceph servers; do not use it.
is part of Ceph, a massively scalable, open-source, distributed
storage system. Please refer to the Ceph documentation at
for more information.
2010-2017, Inktank Storage, Inc. and contributors. Licensed under Creative