Provided by: gnbd-client_1.20060222-0ubuntu5_i386
gnbd_import - manipulate GNBD block devices on a client
gnbd_import imports, lists, and removes GNBDs from the system. GNBD is
similar to the Network Block Device (nbd) in the Linux kernel, except
that it allows multiple clients to connect at once and has a built-in
Restart failed gnbd_recvd processes. Usually, if a gnbd becomes
disconnected, the gnbd_recvd process for that device will
automatically try to reconnect. If that process is killed,
gnbd_import -a will restart it.
List all the IP addresses currently IO fenced from the specified
server. If the sepecified server does not have any IP addresses
fenced, nothing will be returned. If the server machine is not
running gnbd_serv, an error will be returned.
List GNBDs exported by the specified server, along with the port
at which they can be accessed. If the specified server is not
exporting any GNBDs, nothing will be returned. If the server
machine is not running gnbd_serv, an error will be returned.
Print the usage information.
Import all GNBDs which the specified server has exported. This
will not allow a GNBD to be imported if another one with the
same name has already been imported.
List all imported GNBDs. If no options are specified, this is
the default action. There are eight fields for each device:
Device name, Minor #, Proc name, Server, Port, State, Readonly
and Sectors. The Device name is the name that was chosen for the
device when the server exported it. The Minor # is the minor
number for the GNBD on the local machine. The Proc name is the
name for the device that will appear in /proc/partitions, since
Linux does not allow devices in /proc/partitions to have
arbitrary names. NOTE: A GNBD’s Device name will be consistent
across a cluster. Its Minor # and Proc name may not be. Server
and Port are the ones used to communicate with the GNBD’s
server. State describes the state of the device. It has three
variables. The first will either say Open or Closed, depending
on whether the imported GNBD is open or closed. The second will
either say Connected or Disconnected, depending on whether or
not there is a working TCP connection from the device to its
server. When the connection is broken, this variable might not
be immediately updated. The third variable will either say
Pending or Clear, depending on whether or not there are any IO
requests that the GNBD has sent to the server, but which haven’t
been completed yet. Readonly tells whether the gnbd server
exported this device as readonly. Sectors is the device size in
512 bytes sectors.
-n No Cluster
This keeps gnbd_import from trying to contact the cluster
manager. This option is used with -i. NOTE: With this option,
it is not possible to import uncached devices. Warning: This
option should only be used in situations that do not need any
clustering. Attempting to use fence_gnbd to block access to
device imported with this option may silently fail, leading to
possible data corruption in a cluster environment.
This makes gnbd_import run in non-interactive mode. It will no
longer prompt the user before attempting unsafe actions. It is
recommended that you do not use this option.
Change the port to connect to on the server. This option is
used with -c, -e and -i. If the port option is not set,
gnbd_import will try to connect to port 14567 on the server
machine to find the gnbd_serv daemon. You should only need to
use this if you have changed the gnbd_serv port from its
-q Quiet mode.
Only print out errors or questions.
-R Remove All.
Remove all of the imported GNBDs from the system. Only GNBDs
that are in the Closed Disconnected Clear state can be removed
(See the -l option), unless -O is used. Remove All stops after
the first failed remove.
-r [GNBD | LIST]
Remove named GNBD(s) from system. Only GNBDs that are in the
Closed Disconnected Clear state can be removed (See the -l
option), unless the -O option is used. Remove stops after the
first failed remove.
IO fence the specified host. This command is generally invoked
by fenced. WARNING It is not always possible to seamlessly
reconnect a client that has had its connection cut. You should
not execute this command manually unless you know what you are
doing. See the -t option for more information. Once a host is
fenced from a server, it will not be able to access any GNBDs on
that server until it is unfenced (see the -u option).
Fence from Server.
Specify a server for the IO fence (only used with the -s
Unfence the specified host. WARNING: Unfencing a client at the
incorrect time can result in data corruption. In normal
operation, it should never be necessary to run this comman. See
the -t option.
-V Version information.
Print out version information.
-v Verbose output.
Print additional messages during the operation of gnbd_import.
A computer should not import a GNBD device that it exports. Any
significant amount of IO on that device will cause a kernel deadlock.
This is a problem common to most NBDs. Instead, the underlying device
should be used directly. See gnbd_export for more on this.