Re: how to preserve QP over HA events for librdmacm applications

[Pradeep Satyanarayana <pradeeps-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>]

On 09/19/2012 11:14 AM, Atchley, Scott wrote:
> On Sep 19, 2012, at 1:05 PM, "Hefty, Sean"<sean.hefty-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>  wrote:
>
>>> I too would be interested in bringing a QP from error back to a usable state. I
>>> have been debating whether to reconnect using the current RDMA calls versus
>>> trying to transition the existing RC QP.
>>>
>>> I assumed to transition the existing QP that I would need to open a socket to
>>> coordinate the two sides. Is that correct?
>>>
>>> If I were instead to use rdma_connect(), does it require a new CM id or just a
>>> new QP within the same id?

What if you say pre-created a second (fail over) QP for HA purposes all 
under the covers of a single socket? And both QPs were connected before 
the failure. Not sure if that would work with the same CM id though. If 
not, we will need to rdma_connect() the second QP after failure.

By having a second QP and bound to say a different port/device, one 
could survive not just link up/down events, but device failures too. 
Would that be more generic?

Thanks
Pradeep

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