Re: [PATCH 05/14] IB/srp: Maintain a single connection per I_T nexus

[Sebastian Riemer <sebastian.riemer-EIkl63zCoXaH+58JC4qpiA@public.gmane.org>]

On 14.06.2013 19:07, Vu Pham wrote:
[...]
>> For what do you need the same target with multiple pkeys on the same
>> local SRP port?
>>   
> There is no need, it's just a gray area that you can choose to have
> multiple connections to same target using different pkeys (same as dgid)
>> Which other SRP targets exist?
>>   
> 
> Netapp/LSI/Engenio, DDN, TexasMemorySystem Ramsan (IBM), Nimbus, Violin
> Memory, StreamScale
> The last three may be derived from SCST base target.
> 
>> I only know SCST, Solaris COMSTAR and that broken LIO stuff.
>> Does SCST still not support to set the pkey?
>>
>>   
> Yes, I think so
> 
>> Why should we check the dgid?
>>
>>   
> If you want to have multiple connections/qps to same target, but as I
> said above, it's a gray area.
> 
>> Doesn't make any sense to me to connect both target ports to the same
>> local port. 
> What if a target always expose single consistent and unique SRP port
> with tuple <id_ext, ioc_guid>, the ioc_guid part is not derived from any
> of its local HCA's GUID, then you can connect to this target thru
> different HCA ports (different dgid) as different paths to same target.
>
Do you have an example for a target which does it like this or a use
case where this makes sense?

I guess you're proposing here to use a driver global list of target
connections instead of handling this per local SRP port. This would
result in bigger changes which I wouldn't do without a good reason.

>> If you do so, the multipath-tools will crash. Note: This
>> function is called per local SRP port. Perhaps, a note should be added
>> to that function that it only has to be called per local SRP port.

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