Mutipath marked paths as "GHOST paths" and cause "Buffer I/O error" messages in logs

Solution In Progress - Updated -

Environment

  • Red Hat Enterprise Linux 5
  • Red Hat Enterprise Linux 6

Issue

Mutipath maked paths as "GHOST paths" and cause "Buffer I/O error" messages in logs

Resolution

The error can be safely ignored. Do not worry about it.
If you have any concerns, feel free to open a ticket to Red Hat Support Representative.

Root Cause

The paths to those devices in ''ghost" state are passive. All those deices are inaccessible. IO error will be occurred while OS is trying to issue IO requests to them.

What are Ghost paths ? Is it safe to have Ghost paths ?
It is normal to see one or more ghost paths to a device of this type, considering it is RDAC based (ie active/passive).
That said, it is NOT expected to see ALL of the paths ghost. Only those in the passive path group should be ghost. So seeing Ghost paths is not an issue.

Diagnostic Steps

$ cat var/log/messages | grep "read failed"  awk -F'dev' '{print$2}' | awk '{print$1}' | sort | uniq
/sdb:
/sdd:
/sdf:
/sdg:

$ cat sos_commands/devicemapper/multipath_-v4_-ll
......
mpathb (3690b11c0000d4ed20000041f506ccea3) dm-1 DELL,MD36xxf
size=409G features='3 queue_if_no_path pg_init_retries 50' hwhandler='1 rdac' wp=rw
|-+- policy='round-robin 0' prio=6 status=active
| |- 2:0:1:0 sdc 8:32  active ready running
| |- 2:0:3:0 sde 8:64  active ready running
| |- 4:0:2:0 sdh 8:112 active ready running
| `- 4:0:3:0 sdi 8:128 active ready running
`-+- policy='round-robin 0' prio=1 status=enabled
  |- 2:0:2:0 sdd 8:48  active ghost running
  |- 2:0:0:0 sdb 8:16  active ghost running
  |- 4:0:0:0 sdf 8:80  active ghost running
  `- 4:0:1:0 sdg 8:96  active ghost running
......

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