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NAME

       multipath - Device mapper target autoconfig

SYNOPSIS

       multipath         [-v verbosity]         [-d]         [-h|-l|-ll|-f|-F]
       [-p failover|multibus|group_by_serial|group_by_prio|group_by_node_name]
       [device]

DESCRIPTION

       multipath  is used to detect multiple paths to devices for fail-over or
       performance reasons and coalesces them

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

       -p policy
              force maps to specified policy:

                   failover    1 path per priority group

                   multibus    all paths in 1 priority group

                   group_by_serial
                               1 priority group per serial

                   group_by_prio
                               1 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
                               1  priority  group per target node name. Target
                               node      names      are       fetched       in
                               /sys/class/fc_transport/target*/node_name.

       device update only the devmap the path pointed by device is in.  device
              is in the /dev/sdb (as shown by udev in the  $DEVNAME  variable)
              or  major:minor format.  device may alternatively be a multipath
              mapname

SEE ALSO

       udev(8), dmsetup(8) hotplug(8)

AUTHORS

       multipath      was      developed      by      Christophe      Varoqui,
       <christophe.varoqui@free.fr> and others.

                                   July 2006