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Manual Pages  — GCONCAT


gconcat – disk concatenation control utility



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


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!
  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:
  Force the removal of the specified concatenated device.
  Hardcode providers' names in metadata.
  Be more verbose.


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


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


geom(4), loader.conf(5), geom(8), growfs(8), gvinum(8), mount(8), newfs(8), sysctl(8), umount(8)


The gconcat utility appeared in FreeBSD 5.3 .


Pawel Jakub Dawidek <Mt pjd@FreeBSD.org>

GCONCAT (8) May 21, 2004

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