Re: [dm-devel] [PATCH 0/2] 'default' hardware handler for multipath

["Moger, Babu" <Babu Moger netapp com>]

Thanks Hannes. We appreciate your work on this.

> -----Original Message-----
> From: dm-devel-bounces redhat com [mailto:dm-devel-
> bounces redhat com] On Behalf Of Hannes Reinecke
> Sent: Monday, April 02, 2012 11:44 AM
> To: linux-scsi vger kernel org
> Cc: dm-devel redhat com; Mike Snitzer
> Subject: [dm-devel] [PATCH 0/2] 'default' hardware handler for multipath
> 
> This patchset introduces a 'default' hardware handler for dm-multipath.
> Modern storage arrays typically support two failover methods, the original
> proprietary and the modern ALUA-based one.
> The device_handler implementation will currently select the ALUA handler,
> and falling back to the proprietary one if ALUA isn't supported.
> However, in the built-in hardware table for multipath one can specify only
> one hardware handler, causing the original hardware handler to be
> overwritten.
> By specifying a 'default' hardware handler multipath will not try to attach a
> specific hardware handler, but rather using the currently attached on.

I think we still have some issues here. Right now we load the driver
either by adding it in initrd or by using request_module call from device mapper.
If the user passes, hardware_handler   "1 default"  from multipath then request_module will fail. 
How are we going to load the driver if these handlers are not loaded. 

> 
> Hannes Reinecke (2):
>   scsi_dh: Allow NULL hardware handler name in scsi_dh_attach()
>   dm-mpath: Allow 'default' hardware handler
> 
>  drivers/md/dm-mpath.c                 |    8 ++++++--
>  drivers/scsi/device_handler/scsi_dh.c |    8 ++++++--
>  2 files changed, 12 insertions(+), 4 deletions(-)
> 
> --
> 1.7.7
> 
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