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Re: [SOLVED]Re: Only 8 MB/sec write throughput with NetBSD 5.1 AMD64

changing MTU won't help really. it would also cause lots of other problems 
(like fragmentation over your Internet connection) and every device on your 
deity would need to be set for the same MTU. Plus you should be able to push 
way more bandwidth without it. higher MTUs used to be a way to increase 
performance for things like iSCSI but that's not really the case anymore, even 
with 10 Gigabit Ethernet. So even 10 gigabit environments choose not to do 
jumbo frames. 

If your network card is PCI, your bandwidth will be limited to about 200-250 
megabits per second (which is about 25-35 MBytes/s) because of the bus speed. 
PCIe will handle full duplex 1 gigabit no problem.


Sent from my iPhone

On Oct 9, 2011, at 9:05 AM, Manuel Bouyer <> 

> On Sun, Oct 09, 2011 at 08:38:50PM +0530, Ravishankar S wrote:
>> Thanks to all who replied. dd now shows 67 MB/sec!!. However, i have
>> another question. I can now ftp @ 25 MB/sec and it never increases
>> beyond this point. I have a dlink gigabit router and gigabit cards on
>> both ends. client is an  ubuntu laptop
> What does ifconfig -a shows ? You can also test network speed with
> a tool like ttcp, is't more usefull to explore network performances
> than ftp (which mixes performances of different subsystems).
> Note that not all gigabit network adapters or switches can support a
> sustainted link-rate traffic, but 25MB/s looks low anyway
>> Any other areas to explore to increase throughput? I see MTU set at
>> both ends at 1500 - any benefits to increasing it to 3000 - this will
>> enable jumbo frames automatically??
> It should.
> -- 
> Manuel Bouyer <>
>     NetBSD: 26 ans d'experience feront toujours la difference
> --

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