[lustre-discuss] Lustre over 10 Gb Ethernet with and without RDMA

[INKozin]

Ben, is it possible to quantify "faster"?
Understandably, for a single client on an empty cluster it may feel
"faster" but on a busy cluster with many reads and writes in flight I'd
have thought the limiting factor is the back end's throughput rather than
the network, no? As long as the bandwidth to a client is somewhat higher
than the average i/o bandwidth (back end's throughput divided by the number
of clients) the client should be content.

On 19 June 2015 at 14:46, Ben Evans <bevans at cray.com> wrote:

>  It is faster, but I don’t know what price/performance tradeoff is, as I
> only used it as an engineer.
>
>
>
> As an alternative, take a look at RoCE, it does much the same thing but
> uses normal (?) hardware.  It’s still pretty new, though, so you might have
> some speedbumps.
>
>
>
> -Ben Evans
>
>
>
> *From:* lustre-discuss [mailto:lustre-discuss-bounces at lists.lustre.org] *On
> Behalf Of *INKozin
> *Sent:* Friday, June 19, 2015 5:43 AM
> *To:* lustre-discuss at lists.lustre.org
> *Subject:* [lustre-discuss] Lustre over 10 Gb Ethernet with and without
> RDMA
>
>
>
> My question is about performance advantages of Lustre RDMA over 10 Gb
> Ethernet. When using 10 Gb Ethernet to build Lustre, is it worth paying the
> premium for iWARP? I understand that iWARP essentially reduces latency but
> less sure of its specific implications for storage. Would it improve
> performance on small files? Any pointers to representative benchmarks will
> be very appreciated.
>
>
>
> Celsio has released a white paper in which they compare Lustre RDMA over
> 40 Gb Ethernet and FDR IB
>
>
> http://www.chelsio.com/wp-content/uploads/resources/Lustre-Over-iWARP-vs-IB-FDR.pdf
>
> where they claim comparable performance of both.
>
> How much worse the throughput on small block sizes would be without iWARP?
>
>
>
> Thank you
>
> Igor
>
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