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Date:      Thu, 26 May 2016 13:55:47 -0600
From:      John Nielsen <lists@jnielsen.net>
To:        Grzegorz Junka <list1@gjunka.com>
Cc:        freebsd-infiniband@freebsd.org
Subject:   Re: InfiniBand supported hw
Message-ID:  <7C7D1835-52DD-4F27-B0CA-A59650E59639@jnielsen.net>
In-Reply-To: <1063e37f-8a71-0804-b96c-13ef90dcdcb0@gjunka.com>
References:  <9f3323d3-fc01-c1e7-8a93-3132a61c9235@gjunka.com> <A69E3E1D-002C-47CA-A898-0ABF67F64D5B@postgresql.org> <05BB7487-B000-4800-88BD-EC7DEC508160@jnielsen.net> <1063e37f-8a71-0804-b96c-13ef90dcdcb0@gjunka.com>

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> On May 26, 2016, at 12:33 PM, Grzegorz Junka <list1@gjunka.com> wrote:
>=20
>=20
>> On 26/05/2016 17:44, John Nielsen wrote:
>>> On May 26, 2016, at 11:07 AM, Justin Clift <justin@postgresql.org> wrote=
:
>>>=20
>>>> On 26 May 2016, at 14:00, Grzegorz Junka <list1@gjunka.com> wrote:
>>>> Is 500EX-D supported on FreeBSD? I read that it's a Voltaire version an=
d it is the same as Mellanox ConnectX, which supposed to be supported.
>>> Yep, they should work.  You may need to flash them with their Mellanox e=
quivalent
>>> firmware, but I'm not sure.  (doing that flash isn't very hard btw)
>>>=20
>>>> Also, most InfiniBand cards provide two ports. When connecting two comp=
uters together (IPoIB) is it possible to use both ports to double the speed?=

>>> Not sure, as I've not needed to personally.  None of my storage (or othe=
r uses)
>>> even fills one DDR port.  Yet. :)
>>>=20
>>> I *think* the answer to that is yes,
>> It depends on what you mean by "use both ports." You can of course use bo=
th ports at the same time, but if you're envisioning something like an IPoIB=
 version of an Ethernet LAGG I don't think that is supported.
>>=20
>> If you are using the IB for storage protocols, then active/active multipa=
thing is one way to utilize the full bandwidth of multiple ports.
>>=20
>>>> Lastly, is NFS RDMA properly supported on FreeBSD?
>>> Again not sure.  Other people here would likely know. :)
>=20
> Yes, that's exactly what I was hoping for, a sort of LAGG to double the sp=
eed of the link between computer by utilizing both ports together. LAGG is i=
ndependent from the network interface, if I could set up an IPoIB NIC for ea=
ch port separately what could prevent me from creating a LAGG interface on t=
op of them? And if that's not supported, what do people usually do with the o=
ther interface? Just leave it unconnected?

LAGG is designed to work with Ethernet. InfiniBand is a very different layer=
 2 technology with its own advantages and disadvantages. I don't want to get=
 too far out of my depth so I'll just suggest you do your own research on th=
e subject.

How you use the second port is entirely up to you. You can use it for separa=
te applications, for redundancy or higher throughput. In my experience it us=
ually makes sense to give it its own IP. If you want higher bandwidth than a=
 single port can provide then you should at layer 3 or higher for ways to ag=
gregate bandwidth. (You should also do some research on PCI-e throughput. A x=
8 PCI-e 3.0 slot maxes out well before 112Gbit/s.)

As I mentioned previously you can use active/active multipath to get more th=
roughput for block storage applications. You could also run a routing daemon=
 and do ECMP for any layer 3 traffic. Or your particular application may hav=
e other ways to intelligently use two distinct IPoIB paths.






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