[dm-devel] Re: [PATCH 7/7] scsi_dh: attach to hardware handler from dm-mpath

[Hannes Reinecke <hare suse de>]

Chandra Seetharaman wrote:
> Hi Hannes,
>
> Now I see why you want this change in dm-multipath. I think I agree with
> these changes.
Ah. good.

> But, it brings another question: what does dh_state provide ? Help to
> user to see which hardware handler a device is attached to ?
And allowing to attach to a different hardware handler.
Not everyone is running multipathing, but might be interested in the
having the device handler nevertheless.

> I thought more about the scsi_dh_detach function (in the context of my
> earlier comment), adding it would require more housekeeping to associate
> one-to-one mapping between attach and detach. We can leave it the same
> way as the module will be detached when the device disappear eventually.
Why? You can detach with dh_state, too; just do an

echo detach > /sys/block/sdX/device/dh_state

and the hardware handler will detach.
So no additional attribute is required.

Cheers,

Hannes
--
Dr. Hannes Reinecke		      zSeries & Storage
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