[dm-devel] dm-rdac not working?

[Tore Anderson]

* Chandra Seetharaman

> What version of multipath tools are you using ?

   0.4.7.

> Can you attach your multipath.conf file. You should be using the rdac
> path checker instead of the tur path checker.

   Hmm, this was added in 0.4.8...  What's the difference between the
  rdac path checker and the tur checker?  Anyway, it appears to me that
  the problem here is with the kernel hardware handler, not in the
  userspace path checker, wouldn't you agree?  The hardware handler is
  invoked unpon pg init as expected, but fails to do its job.

> Can you attach the o/p of "multipath -ll"

mysql (3600a0b80002984ae0000179c46a68843)
[size=20 GB][features=1 queue_if_no_path][hwhandler=1 rdac]
\_ round-robin 0 [prio=0][enabled]
  \_ 3:0:0:1 sdd 8:48  [active][ready]
  \_ 4:0:0:1 sdh 8:112 [active][ready]
\_ round-robin 0 [prio=6][active]
  \_ 3:0:1:1 sdg 8:96  [active][ready]
  \_ 4:0:1:1 sdj 8:144 [active][ready]
www (3600a0b80002984ae0000179b46a687fb)
[size=45 GB][features=1 queue_if_no_path][hwhandler=1 rdac]
\_ round-robin 0 [prio=0][enabled]
  \_ 3:0:0:0 sdc 8:32  [active][ready]
  \_ 4:0:0:0 sde 8:64  [active][ready]
\_ round-robin 0 [prio=6][active]
  \_ 3:0:1:0 sdf 8:80  [active][ready]
  \_ 4:0:1:0 sdi 8:128 [active][ready]

   This is after the machine has booted, so things have changed around a
  little.  3:0:0:1 and 4:0:0:0 has switched devices, but otherwise it
  looks like it did when I generated the problem.

> I presume 8:64 and 8:112 are the devices corresponding to other paths of
> the device.

   That's right.

> You can see that the MODE_SELECT command is sent and immediately the
> path is failed (which means the MODE_SELECT command has failed).
> 
> And this the same thing that repeats below.

   Yes.  It appears to me it's sending that MODE_SELECT (which I guess is
  like dm-emc's "trespass"?) command when it's  trying to activate the
  pg, but it simply doesn't work, so it's retrying over and over again,
  but in vain.  And after a while ext3 gets remounted r/o and it's game
  over.

Regards
-- 
Tore Anderson
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