GCONCAT(8)              FreeBSD 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
             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), 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>

FreeBSD 13.1-RELEASE-p6          May 21, 2004          FreeBSD 13.1-RELEASE-p6