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

NAME
     gconcat -- disk concatenation control utility

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

DESCRIPTION
     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 de-
     vices.  Once devices are labeled, they will be automatically  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  de-
	      vice'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     See geom(8).

     status   See geom(8).

     load     See geom(8).

     unload   See geom(8).

     Additional options:

     -f      Force the removal of the specified concatenated device.

     -h      Hardcode providers' names in metadata.

     -v      Be more verbose.

SYSCTL VARIABLES
     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  number
	     between  0  and 3 inclusive.  If set to 0 minimal debug information
	     is printed, and if set to 3 the maximum amount of debug information
	     is printed.

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

EXAMPLES
     The following example shows how to configure four disks for automatic  con-
     catenation, 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

     Configure concatenated provider on one disk only.	Create file system.  Add
     two more disks and extend existing file system.

	   gconcat label data /dev/da0
	   newfs /dev/concat/data
	   gconcat label data /dev/da0 /dev/da1 /dev/da2
	   growfs /dev/concat/data

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

HISTORY
     The gconcat utility appeared in FreeBSD 5.3.

AUTHORS
     Pawel Jakub Dawidek <pjd@FreeBSD.org>

FreeBSD 8.2			  May 21, 2004			      GCONCAT(8)
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