[Lustre-discuss] Questions about the LNET routing

[teng wang]

Hi Andrus, thanks for your answer.


Without bonding, is there any preference

for LNET to route from the two interfaces?

Even when we bond the two interfaces together,

I think LNET should still choose between the different

interfaces, although they share the same address.

Is there any preference in this situation?


Thanks,

Teng

On Thu, Feb 19, 2015 at 3:55 PM, Andrus, Brian Contractor <bdandrus at nps.edu>
wrote:

>  Teng,
>
>
>
> I believe it would depend on how you have your interfaces configured.
>
>
>
> I seems that you have them both on the same subnet and being accessed by
> the same client.
>
> Is this the case?
>
>
>
> If they are on the same subnet, I would expect you would bond them (bond0)
> rather than have two separate IPs for them. Then you get to control
> how/where the data flows at the networking level.
>
>
>
> You may want to check on the nodes to see what they see. (lctl peer_list)
>
>
>
> If they are different subnets or networks, you can set that in the options
> for the lustre module for lnet.
>
> For example, we have both ib and tcp. I give ib the priority for the best
> performance, but if ib is unavailable, it falls back to tcp. That could
> just as well be two Ethernet cards on two networks as well.
>
>
>
>
>
> Brian Andrus
>
> ITACS/Research Computing
>
> Naval Postgraduate School
>
> Monterey, California
>
> voice: 831-656-6238
>
>
>
>
>
>
>
>
>
> *From:* lustre-discuss-bounces at lists.lustre.org [mailto:
> lustre-discuss-bounces at lists.lustre.org] *On Behalf Of *teng wang
> *Sent:* Thursday, February 19, 2015 1:28 PM
> *To:* lustre-discuss at lists.lustre.org
> *Subject:* [Lustre-discuss] Questions about the LNET routing
>
>
>
> I have a basic question about the LNET.  Will the data belonging
>
> to the same object be routed from the same interface? For example,
>
> if a node has multiple network interfaces and two processes are
>
> running on the same node writing to the same shared file, striped
>
> across 1 OST.
>
> Process 1 writes like:
>
> write chunk1
>
> write chunk2
>
>
>
> Process 2 writes like:
>
> write chunk3
>
> write chunk4
>
> If Process 1 and Process2 are pinned to two different network interfaces,
>
> say Eth0 and Eth1. Then from the OSC side, will these chunks be routed
>
> to the OST from the same interface (E.g. All the four chunks through
>
> Eth0)?  If so, what if they write different objects that come to the same
>
> OST (E.g. Process1 write File1, Process2 write file2, file1 and file2 are
>
> striped over the same OST)?
>
>
>
> Thanks,
>
> Teng
>
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