GCONCAT(8)

NAME

     gconcat -- disk concatenation control utility

SYNOPSIS

     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]

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 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.

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, both included.  If set to 0 minimal debug
	     information is printed, and if set to 3 the maximum amount of
	     debug information in printed.

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

DIAGNOSTICS

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

SEE ALSO

     geom(4), loader.conf(5), geom(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>