"sd" device is not available in `/proc/partitions` after SAN failure but the corresponding entry is available in `/proc/scsi/scsi` and in `/dev`

Solution Verified - Updated -

Environment

  • Red Hat Enterprise Linux 6

Issue

  • "sd" device is not available in /proc/partitions after SAN failure but the corresponding entry is available in /proc/scsi/scsi and in /dev

Resolution

Remove the devices whose entry is missing from /proc/partitions and scan the scsi bus to add again.

Please refer How to rescan the SCSI bus to add or remove a SCSI device without rebooting the computer for removing and adding the scsi devices.

Diagnostic Steps

System have 4 luns and each lun having 2 paths.

# multipath -ll
mpathd (3600c0ff0001187d86123bc5201000000) dm-6 HP,P2000 G3 FC
size=2.8G features='1 queue_if_no_path' hwhandler='0' wp=rw
`-+- policy='round-robin 0' prio=130 status=active
  |- 7:0:1:252 sdh 8:112 active ready running
  `- 7:0:0:252 sdd 8:48  active ready running
mpatho (3600c0ff0001187d84e98375401000000) dm-2 HP,P2000 G3 FC
size=954M features='1 queue_if_no_path' hwhandler='0' wp=rw
`-+- policy='round-robin 0' prio=130 status=active
  |- 7:0:1:13  sdg 8:96  active ready running
  `- 7:0:0:13  sdc 8:32  active ready running
mpathb (3600c0ff0001187d8d02fc25201000000) dm-4 HP,P2000 G3 FC
size=1.9G features='1 queue_if_no_path' hwhandler='0' wp=rw
`-+- policy='round-robin 0' prio=130 status=active
  |- 7:0:1:0   sdf 8:80  active ready running
  `- 7:0:0:0   sdb 8:16  active ready running
mpathf (3600c0ff0001187d806f7ba5201000000) dm-3 HP,P2000 G3 FC
size=954M features='1 queue_if_no_path' hwhandler='0' wp=rw
`-+- policy='round-robin 0' prio=130 status=active
  |- 7:0:0:254 sde 8:64  active ready running
  `- 7:0:1:254 sdi 8:128 active ready running

# cat /proc/partitions  |grep sd |grep -v sda
   8       32     976560 sdc
   8       16    1953120 sdb
   8       48    2929680 sdd
   8       64     976560 sde
   8       80    1953120 sdf
   8       96     976560 sdg
   8      112    2929680 sdh
   8      128     976560 sdi

Disable the port on the switch where HBA is connected.

As soon as we reset/disable this port it removes all scsi devices from system.

# multipath -ll
mpathd (3600c0ff0001187d86123bc5201000000) dm-6 
size=2.8G features='1 queue_if_no_path' hwhandler='0' wp=rw
mpathb (3600c0ff0001187d8d02fc25201000000) dm-4 
size=1.9G features='1 queue_if_no_path' hwhandler='0' wp=rw
mpathf (3600c0ff0001187d806f7ba5201000000) dm-3 
size=954M features='1 queue_if_no_path' hwhandler='0' wp=rw

here fdisk -l might hang as well.

# cat /proc/partitions  |grep sd |grep -v sda
#

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