.TH "CEPHFS" "8" "September 22, 2011" "dev" "Ceph"
.SH NAME
cephfs \- ceph file system options utility
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.SH SYNOPSIS
.nf
\fBcephfs\fP [ \fIpath\fP \fIcommand\fP \fIoptions\fP ]
.fi
.sp
.SH DESCRIPTION
.sp
\fBcephfs\fP is a control utility for accessing and manipulating file
layout and location data in the Ceph distributed file system.
.sp
Choose one of the following three commands:
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.IP \(bu 2
\fBshow_layout\fP View the layout information on a file or directory
.IP \(bu 2
\fBset_layout\fP Set the layout information on a file or directory
.IP \(bu 2
\fBshow_location\fP View the location information on a file
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.SH OPTIONS
.sp
Your applicable options differ depending on whether you are setting or viewing layout/location.
.SS Viewing options:
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.TP
.B \-l \-\-offset
Specify an offset for which to retrieve location data
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.SS Setting options:
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.TP
.B \-u \-\-stripe_unit
Set the size of each stripe
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.TP
.B \-c \-\-stripe_count
Set the number of stripes per object
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.TP
.B \-s \-\-object_size
Set the size of the objects to stripe across
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.TP
.B \-p \-\-pool
Set the pool (by numeric value, not name!) to use
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.TP
.B \-o \-\-osd
Set the preferred OSD to use as the primary
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.SH LIMITATIONS
.sp
When setting layout data, the specified stripe unit and stripe count
must multiply to the size of an object. Any parameters you don\(aqt set
explicitly are left at the system defaults.
.sp
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 \fIany\fP data to
it. Truncating a file does not allow you to change the layout either.
.sp
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.
.sp
You\(aqll 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\(aqs space
utilization.
.SH AVAILABILITY
.sp
\fBcephfs\fP is part of the Ceph distributed file system. Please refer
to the Ceph wiki at \fI\%http://ceph.newdream.net/wiki\fP for more
information.
.SH SEE ALSO
.sp
\fBceph\fP(8)
.SH COPYRIGHT
2011, New Dream Network
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