GCONCAT(8)		  BSD 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 devices.  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
	      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     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 num‐
	     ber between 0 and 3 inclusive.  If set to 0 minimal debug infor‐
	     mation 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
     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

     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), gvinum(8), mount(8),
     newfs(8), sysctl(8), umount(8)

HISTORY
     The gconcat utility appeared in FreeBSD 5.3.

AUTHORS
     Pawel Jakub Dawidek ⟨pjd@FreeBSD.org⟩

BSD				 May 21, 2004				   BSD