[mythtv-users] NFS and remote backend

Wade Maxfield mythtv at hotblack.co.nz
Fri Jan 11 21:43:52 UTC 2008

John Drescher wrote:
>> On my gigabit network, NFS from my backend (Athlon64 X2 4600+, 2GB RAM)
>> to a G5 tower gets about 18MB/s for any size transfer from 350MB to
>> 1.5GB.
> This is slow (compared to what I get between 2 Athlon64 computers). I
> assume that is because the G5 is a few years old.

I don't think it is because the G% is old, as G5 to G5 over AFP I can 
get 50MB/s+, and from a Xeon Xserve to the G5 I can get 60MB/s+ sustained.

>> If I then delete the file from the G5 and copy the exact same
>> file again I reach speeds of up to 56MB/s (according to IPNetMonitor - a
>> Mac network tool which graphs network transfers in real time - so it's
>> not just a cached file at the Mac end)
> I would say this probably is because of caching.
> John

Caching maybe at the server end, since I can see the data being 
transfered over the network.

To add another data point, while one copy is going at 16MB/s I can 
initiate another copy for a different file (same backend & hard drive to 
a separate drive on the G5) and it will also get around 14-16MB/s for a 
total network throughput of around 30-32MB/s

So I don't think it's a limitation of my network adaptors, switch or 
cabling (or older G5 machines/etc).  I'm wondering if there is some sort 
of throttling or threading at play?  Something to ensure responsiveness 
or ability to handle multiple requests from multiple clients and not 
dedicate all resources/performance for a single client/transfer?

  - Wade

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