Re: dm-rdac not working?

[Tore Anderson <tore@linpro.no>]

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* 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

[-- Attachment #2: multipath.conf --]
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# This file is managed by puppet, any local changes will be lost

defaults {
	user_friendly_names	yes
}

defaults {
	multipath_tool		"/sbin/multipath -v0"
	udev_dir		/dev
	polling_interval	10
	rr_wmin_io		100
}

blacklist {
	devnode			"^(ram|raw|loop|fd|md|dm-|sr|scd|st)[0-9]*"
	devnode			"^hd.*"
	devnode			"^cciss!c[0-9]d[0-9]*[p[0-9]*]"
	device {
		vendor			IBM-ESXS
	}
}

multipaths {
	multipath {
		wwid			3600a0b80002984ae0000179b46a687fb
		alias			www
	}
	multipath {
		wwid			3600a0b80002984ae0000179c46a68843
		alias			mysql
	}
}

devices {
	device {
		vendor			DGC
		product			RAID.*
		hardware_handler	"1 emc"
		prio_callout		"/sbin/mpath_prio_emc /dev/%n"
		path_checker		emc_clariion
		path_grouping_policy	group_by_prio
		failback		immediate
		no_path_retry		queue
	}
	device {
		vendor			SUN
		product			CSM200_R
		hardware_handler	"1 rdac"
		prio_callout		"/usr/local/sbin/mpath_prio_rdac /dev/%n"
		path_checker		tur
		path_grouping_policy	group_by_serial
		failback		immediate
		no_path_retry		queue
	}
}

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