.TH CEPHFS 8
.SH NAME
cephfs \- ceph file system options utility
.SH SYNOPSIS
.B cephfs
[ \fIpath \fIcommand \fBoptions]
.SH DESCRIPTION
.B 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:
.TP
\fBshow_layout \fPView the layout information on a file or directory
.TP
\fBset_layout  \fPSet the layout information on a file or directory.
.TP
\fBshow_location \fPView the location information on a file

.SH OPTIONS
Your applicable options differ depending on whether you are setting
or viewing layout/location.
.TP
\fBViewing options:
.IP
\fB\-l \--offset
\fPSpecify an offset for which to retrieve location data

.TP
\fBSetting options:
.IP
\fB\-u
\--stripe_unit \fP
Set the size of each stripe
.IP
\fB\-c
\--stripe_count \fP
Set the number of stripes per object
.IP
\fB\-s
\--object_size \fP
Set the size of the objects to stripe across
.IP
\fB\-p
\--pool \fP
Set the pool (by numeric value, not name!) to use
.IP
\fB\-o
\--osd \fP
Set the preferred OSD to use as the primary

.SH 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.

.SH AVAILABILITY
.B cephfs
is part of the Ceph distributed file system.  Please refer to the Ceph wiki at
http://ceph.newdream.net/wiki for more information.
.SH SEE ALSO
.BR ceph (8)