[dm-devel] mechanism for multipath to pass information to hardware handler

[James Bottomley]

On Fri, 2009-06-26 at 12:45 -0700, Chandra Seetharaman wrote:
> Yes, Mike Christie and I were aware of this and it was one of the issue
> we were trying to resolve before we pushed scsi_dh interface upstream.
> (It is little complicated as we need the parameters to be set per
> vendor-product tuple).
> 
> The original code I ported to scsi_dh interface was from Ed Goggin(who
> was working for EMC then). IIRC, he was also aware of this issue.
> 
> When we pushed scsi_dh interface, we did get few of the EMC folks (on
> Cc) to review/test the code and they did, and this issue was not seen as
> a problem. 
> 
> We wanted to get back to that issue sometime later, got busy with other
> things, and it disappeared from my list of things-to-do as the
> regression was not seen as an issue (till now :)... I will get back to
> it.

One way around this might simply be to make the device_handlers create a
sysfs interface for additional parameters.  Then the multipath command
can feed them (or in a pinch, users relying on the features can pass
them in manually).  Right at the moment having no possible work around
does appear to be an issue.

James