[OpenAFS] Re: about openafs , fileserver process , performance
Thu, 20 Feb 2014 20:21:35 +0100
Thanks for this information,
RTT is around 1ms-2ms , so i near the theorical throughput,
2014-02-20 19:20 GMT+01:00 Andrew Deason <email@example.com>:
> On Thu, 20 Feb 2014 14:33:15 +0100
> nicolas prochazka <firstname.lastname@example.org> wrote:
>> I do some benchmark ,
>> cat /afs/mycell.com/bigfile > /dev/null on openafs clients
>> and i see a bottleneck of 25MBytes/s on server side ( fileserver process) .
>> My ethernet link are 1Gbit/s
>> How can I suppress this bottleneck ?
> Do you know what the RTT is between the server? (just 'ping' the server
> for an approximation)
> The maximum theoretical throughput you'll get from openafs right now is
> somewhere around ((32 * 1400) / RTT) bytes per second (due to some
> limitations in the transport mechanism). That means if your RTT is on
> the order of 10ms, the maximum throughput you'll see is is 4 or 5 MiB/s.
> If your RTT is around 1ms, you'll see a maximum of around 40 or 50
> MiB/s. That is the theoretical max, so the actual throughput you'll see
> will be less.
> There are other potential bottlenecks, of course, but that is often the
> biggest factor when someone is surprised at the low transfer rates that
> they see. There are some efforts underway to alleviate those
> restrictions, but you can't do much about it just by "tuning" clients or
> servers etc.
> Andrew Deason
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