==== Add device ====

<code>
echo "- - -" > /sys/class/scsi_host/host2/scan
echo "- - -" > /sys/class/scsi_host/host3/scan
echo "- - -" > /sys/class/scsi_host/host4/scan
</code>

<code>
[root@ces7gdfdpads block]# multipath -ll
mpathe (360000970000292603038533030333535) dm-19 EMC,SYMMETRIX
size=553G features='1 queue_if_no_path' hwhandler='0' wp=rw
`-+- policy='round-robin 0' prio=1 status=active
  |- 2:0:2:1   sdn 8:208 active ready running
  |- 2:0:3:1   sdo 8:224 active ready running
  |- 3:0:3:1   sdp 8:240 active ready running
  `- 3:0:2:1   sdq 65:0  active ready running
mpathd (360000970000292603038533030304630) dm-18 EMC,SYMMETRIX
size=1.9M features='1 queue_if_no_path' hwhandler='0' wp=ro
`-+- policy='round-robin 0' prio=1 status=active
  |- 3:0:3:0   sdk 8:160 active ready running
  |- 3:0:2:0   sdj 8:144 active ready running
  |- 2:0:2:0   sdl 8:176 active ready running
  `- 2:0:3:0   sdm 8:192 active ready running
mpathc (360000970000292601159533030304130) dm-11 EMC,SYMMETRIX
size=2.8M features='1 queue_if_no_path' hwhandler='0' wp=ro
`-+- policy='round-robin 0' prio=1 status=active
  |- 3:0:0:239 sdf 8:80  active ready running
  |- 3:0:1:239 sdi 8:128 active ready running
  |- 2:0:1:239 sdh 8:112 active ready running
  `- 2:0:0:239 sdd 8:48  active ready running
  </code>

==== Remove device ====

<code>
multipath -f mpathb
echo "1" > /sys/block/sde/device/delete 
echo "1" > /sys/block/sdb/device/delete 
echo "1" > /sys/block/sdc/device/delete 
echo "1" > /sys/block/sdg/device/delete 
</code>