gnbd_import man page on YellowDog

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gnbd_import(8)							gnbd_import(8)

NAME
       gnbd_import - manipulate GNBD block devices on a client

SYNOPSIS
       gnbd_import [OPTION]...

DESCRIPTION
       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
       fence command.

OPTIONS
       -a     Validate.

	      Restart failed gnbd_recvd processes. Usually, if a gnbd  becomes
	      disconnected,  the gnbd_recvd process for that device will auto‐
	      matically	 try  to  reconnect.  If  that	process	  is   killed,
	      gnbd_import -a will restart it.

       -c server
	      Check fenced.

	      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.

       -e server
	      List exported.

	      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.

       -h     Help.

	      Print the usage information.

       -i server
	      Import.

	      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.

       -l     List.

	      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	 arbi‐
	      trary  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 man‐
	      ager.  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  cluster‐
	      ing.  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.

       -O     Override

	      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.

       -p     Port.

	      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
	      default.

       -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.

	      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.

       -s host
	      Fence.

	      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).

       -t server
	      Fence from Server.

	      Specify a server for  the	 IO  fence  (only  used	 with  the  -s
	      option).

       -u host
	      Unfence.

	      Unfence  the  specified host. WARNING: Unfencing a client at the
	      incorrect time can result in data corruption.  In normal	opera‐
	      tion,  it	 should never be necessary to run this comman. See the
	      -t option.

       -U GNBD
	      Get UID.

	      Gets the Universal Identifier for the specified GNBD.  This com‐
	      mand is used by dm-multipathing to create multipath maps.

       -V     Version information.

	      Print out version information.

       -v     Verbose output.

	      Print additional messages during the operation of gnbd_import.

SEE ALSO
       gnbd_export(8)

BUGS
       A  computer  should not import a GNBD device that it exports.  Any sig‐
       nificant 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.

								gnbd_import(8)
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