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 config

uration. 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 per

formed:

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 speci

fied 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 com

mand 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 de

vice.

-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
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), 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>

BSD May 21, 2004

BSD