[dm-devel] EMC Clariion ghost devices

[Lars Marowsky-Bree]

On 2005-07-29T15:28:03, Joel Becker <Joel.Becker at oracle.com> wrote:

> 	I've just tried using the multipath-tools (SLES9 SP2,
> multipath-tools-0.4.4-0.22) with my EMC clariion.  Now, this clariion is
> an active/passive system, and the second path is showing a ghost LUN 0
> (this is expected).

"WFM". I actually tested the SP2 code on a CLARiiON, it's my development
box ;-) The version of multipath-tools on SLES9 SP2 is not quite 0.4.4
from upstream, though, but with some fixes pulled in.

Have you seen
http://portal.suse.com/sdb/en/2005/04/sles_multipathing.html ?

> 	During normal boot, the device (/dev/sdap) returns an I/O error
> when the kernel tries to get the partition table.  No problem.  If later
> someone scans the disk, they get an I/O error.  No problem.

Yeah, this is ugly and annoying, but harmless.

> 	Then I fire up multipathd and multipath.  Multipath creates a dm
> device for the ghost, and tries to run kpartx on it.  That kpartx hangs.
> In fact, I don't know how, but it ends up in a frozen I/O state.  It's
> unkillable.

That should not happen(tm). Where does it hang according to sysrq-t?

(kpartx supposedly is run against the dm-multipath table and not against
sdap, so it should already benefit from the multipath protection...)

"sg_inq -P /dev/sdap" might also be worth a try, what does it report for
the various paths?

Is that a LUN 0 backed by actual storage or a LUN_Z?


Sincerely,
    Lars Marowsky-Brée <lmb at suse.de>

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