[Bug 1032550] Re: [multipath] failed to get sysfs information

[Peter Petrakis]

Hi Ronald,

Sorry I haven't been timely, this is the best I can do with community level support
 If kdump isn't launching even in the most trivial case then you have to start from zero.

is crashkernel even configured? 
 * grep  crash /proc/crashkernel

How much memory do you have, could you assign more memory to the crash kernel?
 * http://lxr.linux.no/linux+v3.7.1/Documentation/kdump/kdump.txt#L270
 * 256MB would be preferable

Can you even kexec at all?
 * kexec -p # loads the panic kernel, man kexec

If you boot your system with  maxcpus=1  (I think that's it) and pretend you're
a uniprocessor system, will kexec load?

Can you attach a serial console to your machine and post the output?

In /etc/init.d/kdump
        # Append kdump_needed for initramfs to know what to do, and add
        # maxcpus=1 to keep things sane.
        APPEND="$APPEND kdump_needed maxcpus=1 irqpoll reset_devices"

Start adjusting these variables, like remove 'reset_devices', reload the
kexec kernel (service kdump restart), and systematically remove variables
(except kdump_needed) noting the change in the kernel output.

Is this an enterprise server with an NMI button? If you configure "panic on nmi"
pressing that button, that will definitely change the base variables used to
launch kexec.

Folks thought Stratus was a bit overkill, having a complete mirror of CPU/Memory
operating in lockstep for HA. The nice thing about it is if the primary ever did crash,
we would literally hold that unit in stasis, reboot on the other unit, and reap the
dump from it's preserved memory, works 100% and automatic. Be nice to have
right about now.

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https://bugs.launchpad.net/bugs/1032550

Title:
  [multipath]  failed to get sysfs information

Status in “multipath-tools” package in Ubuntu:
  In Progress

Bug description:
  when shutdown switch port of host HBA,  multippath-tool can't get
  correct information  of subpath. by check the "multipath" output,
  some storage device type info disapppear and the failed path always
  stay in path group and don't be clear out.


  mpath2 (3600601601c102900944737e4a73fe011) dm-51 ,
  size=6.0G features='1 queue_if_no_path' hwhandler='1 emc' wp=rw
  |-+- policy='round-robin 0' prio=1 status=active
  | |- #:#:#:#  -    #:#     failed faulty running
  | `- 5:0:2:5  sdcu 70:32   active ready running
  `-+- policy='round-robin 0' prio=0 status=enabled
    |- 5:0:3:5  sdfa 129:192 active ready running
    `- #:#:#:#  -    #:#     failed faulty running
  mpath38 (3600601601c1029008eb6dbe8ae3fe011) dm-59 DGC,VRAID
  size=5.0G features='1 queue_if_no_path' hwhandler='1 emc' wp=rw
  |-+- policy='round-robin 0' prio=1 status=active
  | `- 5:0:2:13 sddf 70:208  active ready running
  `-+- policy='round-robin 0' prio=0 status=enabled
    `- 5:0:3:13 sdfk 130:96  active ready running
  mpath63 (360000970000198700131533030303932) dm-13 EMC,SYMMETRIX
  size=5.6G features='0' hwhandler='0' wp=rw
  `-+- policy='round-robin 0' prio=1 status=active
    |- 5:0:0:8  sdl  8:176   active ready running
    `- 5:0:1:8  sdbd 67:112  active ready running
  mpath95 (360000970000198700131533030323445) dm-43 ,
  size=898M features='0' hwhandler='0' wp=rw
  `-+- policy='round-robin 0' prio=1 status=active
    |- #:#:#:#  -    #:#     failed faulty running
    |- #:#:#:#  -    #:#     failed faulty running
    |- 5:0:0:38 sdas 66:192  active ready running
    `- 5:0:1:38 sdck 69:128  active ready running


  Same time, the syslog show many

  ---------------
  Aug  2 18:25:16 Linux51 multipathd: sdht: failed to get sysfs information
  Aug  2 18:25:16 Linux51 multipathd: sdht: unusable path
  ... ...
  ---------------

  After path  recover, all failed path come back without problem.  there
  is no IP blocked and error happend during fail/recover period.

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