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GCONCAT(8)		FreeBSD	System Manager's Manual		    GCONCAT(8)

     gconcat --	disk concatenation control utility

     gconcat create [-v] name prov prov	[prov [...]]
     gconcat destroy [-fv] name	[name [...]]
     gconcat label [-hv] name prov prov	[prov [...]]
     gconcat stop [-fv]	name [name [...]]
     gconcat clear [-v]	prov [prov [...]]
     gconcat dump prov [prov [...]]
     gconcat list [name	[...]]
     gconcat load [-v]
     gconcat unload [-v]

     The gconcat utility is used for device concatenation configuration.  The
     concatenation can be configured using two different methods: ``manual''
     or	``automatic''.	When using the ``manual'' method, no metadata are
     stored on the devices, so the concatenated	device has to be configured by
     hand every	time it	is needed.  The	``automatic'' method uses on-disk
     metadata to detect	devices.  Once devices are labeled, they will be auto-
     matically detected	and configured.

     The first argument	to gconcat indicates an	action to be performed:

     create   Concatenate the given devices with specified name.  This is the
	      ``manual'' method.  The kernel module geom_concat.ko will	be
	      loaded if	it is not loaded already.

     label    Concatenate the given devices with the specified name.  This is
	      the ``automatic''	method,	where metadata are stored in every
	      device's last sector.  The kernel	module geom_concat.ko will be
	      loaded if	it is not loaded already.

     stop     Turn off existing	concatenate device by its name.	 This command
	      does not touch on-disk metadata!

     destroy  Same as stop.

     clear    Clear metadata on	the given devices.

     dump     Dump metadata stored on the given	devices.

     list     List all or the given currently configured devices.

     load     Load geom_concat.ko kernel module.

     unload   Unload geom_concat.ko kernel module.

     Additional	options:

     -f	     Force the removal of the specified	concatenated device.

     -h	     Hardcode providers' names in metadata.

     -v	     Be	more verbose.

     The following sysctl(8) variables can be used to control the behavior of
     the CONCAT	GEOM class.  The default value is shown	next to	each variable.

     kern.geom.concat.debug: 0
	     Debug level of the	CONCAT GEOM class.  This can be	set to a num-
	     ber between 0 and 3, both included.  If set to 0 minimal debug
	     information is printed, and if set	to 3 the maximum amount	of
	     debug information in printed.

     The following example shows how to	configure four disks for automatic
     concatenation, create a file system on it,	and mount it:

	   gconcat label -v data /dev/da0 /dev/da1 /dev/da2 /dev/da3
	   newfs /dev/concat/data
	   mount /dev/concat/data /mnt
	   umount /mnt
	   gconcat stop	data
	   gconcat unload

     Exit status is 0 on success, and 1	if the command fails.

     geom(4), loader.conf(5), geom(8), mount(8), newfs(8), sysctl(8),
     umount(8),	vinum(8)

     The gconcat utility appeared in FreeBSD 5.3.

     Pawel Jakub Dawidek <>

FreeBSD	11.0			 May 21, 2004			  FreeBSD 11.0


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