Provided by: gnbd-client_1.20060222-0ubuntu5_i386 bug


       gnbd_import - manipulate GNBD block devices on a client


       gnbd_import [OPTION]...


       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.


       -a     Validate.

              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.

       -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  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
              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.

       -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

       -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.

       -s host

              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

       -u host

              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.