CEPHFS(8) Ceph CEPHFS(8)NAMEcephfs - ceph file system options utility
SYNOPSIScephfs [ path command options ]
DESCRIPTIONcephfs 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. Trun‐
cating 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 pre‐
ferred OSD for placement. This is allowed but is not recommended since
it can dramatically unbalance your storage cluster's space utilization.
AVAILABILITYcephfs is part of the Ceph distributed file system. Please refer to the
Ceph wiki at http://ceph.newdream.net/wiki for more information.
SEE ALSOceph(8)COPYRIGHT
2011, New Dream Network
dev September 22, 2011 CEPHFS(8)