NAME

       multipath - Device mapper target autoconfig.

SYNOPSIS

       multipath               [-v verbosity]               [-b bindings_file]               [-d]
       [-h|-l|-ll|-f|-t|-F|-B|-c|-C|-q|-r|-i|-a|-u|-U|-w|-W]
       [-p failover|multibus|group_by_serial|group_by_prio|group_by_node_name]       [-R retries]
       [device]

DESCRIPTION

       multipath is used to detect and coalesce multiple  paths  to  devices,  for  fail-over  or
       performance reasons.

OPTIONS

       -v level
              Verbosity, print all paths and multipaths:

                   0           No output.

                   1           Print the created or updated multipath names only, for use to feed
                               other tools like kpartx.

                   2 +         Print all info: detected paths, coalesced  paths  (ie  multipaths)
                               and device maps.

       -h     Print usage text.

       -d     Dry run, do not create or update devmaps.

       -l     Show  the  current  multipath  topology  from  information fetched in sysfs and the
              device mapper.

       -ll    Show the current multipath topology from  all  available  information  (sysfs,  the
              device mapper, path checkers ...).

       -f     Flush a multipath device map specified as parameter, if unused.

       -F     Flush all unused multipath device maps.

       -t     Display the currently used multipathd configuration.

       -r     Force devmap reload.

       -i     Ignore WWIDs file when processing devices.

       -B     Treat the bindings file as read only.

       -b bindings_file
              Set    user_friendly_names    bindings    file    location.     The    default   is
              /etc/multipath/bindings.

       -c     Check if a block device should be a path in a multipath device.

       -C     Check if a multipath device has usable paths. This can be used to test  whether  or
              not  I/O on this device is likely to succeed. The command itself doesn't attempt to
              do I/O on the device.

       -q     Allow device tables with queue_if_no_path when multipathd is not running.

       -a     Add the WWID for the specified device to the WWIDs file.

       -u     Check if the device specified in the program environment should  be  a  path  in  a
              multipath device.

       -U     Check if the device specified in the program environment is a multipath device with
              usable paths. See -C.

       -w     Remove the WWID for the specified device from the WWIDs file.

       -W     Reset the WWIDs file to only include the current multipath devices.

       -p policy
              Force new maps to use the specified policy:

                   failover    One path per priority group.

                   multibus    All paths in one priority group.

                   group_by_serial
                               One priority group per serial number.

                   group_by_prio
                               One priority group per priority value. Priorities  are  determined
                               by  callout programs specified as a global, per-controller or per-
                               multipath option in the configuration file.

                   group_by_node_name
                               One priority group per target node name.  Target  node  names  are
                               fetched in /sys/class/fc_transport/target*/node_name.

              Existing maps are not modified.

       -R retries
              Number of times to retry flushing multipath devices that are in-use. The default is
              0.

       device Update only the devmap specified by device, which is either:

                   •      A devmap name.

                   •      A path associated with the desired devmap; the path may be  in  one  of
                          the following formats:

                               •      /dev/sdX

                               •      major:minor

SEE ALSO

       multipathd(8), multipath.conf(5), kpartx(8), udev(8), dmsetup(8), hotplug(8).

AUTHORS

       multipath-tools  was  developed by Christophe Varoqui <christophe.varoqui@opensvc.com> and
       others.