[dm-devel] multibus / failover and EMC CX600

[Hannes Reinecke]

Tore Anderson wrote:
> * Gerald Nowitzky
> 
>> What I'd like to have is multibus via HBA-A -> SW-A -> SP-A  and
>> HBA-B -> SW-B -> SP-A to the active SP and, in case both paths to the
>> active SP fail, a trespas of my LUN to SP-B, multibus to the other
>> SP-B and vice versa.
> 
> Try the following:
> 
>   prio_callout "/sbin/mpath_prio_emc /dev/%n"
>   path_grouping_policy group_by_prio
> 
> The -EEXIST message is a kernel bug, see the thread starting at
> <http://lkml.org/lkml/2007/8/14/106> for more information.  It might be
> possible to work around it by disabling async SCSI scanning, if not
> there's a patch from Matthew Wilcox that removed most of those -EEXIST
> errors (but not all the corner cases).
> 
> It kinda sucks that the kernel removes the SCSI devices pointing to
> blocked rports.  Wonder if it's possible to disable that somehow...
> 
That's the dev_loss_tmo setting. Just increase it to something to
your liking.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		      zSeries & Storage
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