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https://github.com/ceph/ceph
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69 lines
2.1 KiB
Groff
69 lines
2.1 KiB
Groff
.TH CEPHFS 8
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.SH NAME
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cephfs \- ceph file system options utility
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.SH SYNOPSIS
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.B cephfs
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[ \fIpath \fIcommand \fBoptions]
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.SH DESCRIPTION
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.B cephfs
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is a control utility for accessing and manipulating file layout
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and location data in the Ceph distributed file system.
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Choose one of the following three commands:
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.TP
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\fBshow_layout \fPView the layout information on a file or directory
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.TP
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\fBset_layout \fPSet the layout information on a file or directory.
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.TP
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\fBshow_location \fPView the location information on a file
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.SH OPTIONS
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Your applicable options differ depending on whether you are setting
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or viewing layout/location.
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.TP
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\fBViewing options:
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.IP
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\fB\-l \--offset
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\fPSpecify an offset for which to retrieve location data
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.TP
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\fBSetting options:
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.IP
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\fB\-u
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\--stripe_unit \fP
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Set the size of each stripe
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.IP
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\fB\-c
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\--stripe_count \fP
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Set the number of stripes per object
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.IP
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\fB\-s
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\--object_size \fP
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Set the size of the objects to stripe across
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.IP
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\fB\-p
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\--pool \fP
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Set the pool (by numeric value, not name!) to use
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.IP
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\fB\-o
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\--osd \fP
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Set the preferred OSD to use as the primary
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.SH LIMITATIONS
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When setting layout data, the specified stripe unit and stripe count
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must multiply to the size of an object. Any parameters you don't set explicitly are left at the system defaults.
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Obviously setting the layout of a file and a directory means different things.
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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.
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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.
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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.
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.SH AVAILABILITY
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.B cephfs
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is part of the Ceph distributed file system. Please refer to the Ceph wiki at
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http://ceph.newdream.net/wiki for more information.
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.SH SEE ALSO
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.BR ceph (8)
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