[CentOS] nfs slow?

Stefan Held obi at unixkiste.org
Wed Dec 10 20:21:10 UTC 2008


Am Mittwoch, den 10.12.2008, 15:01 -0500 schrieb John Kordash:
> > 2.) Use TCP, UDP Transmits are often slow these days. (mount
> > option tcp)
> 
One Key Fact for UDP being much faster then TCP was 

a.) The Lack of performant Hardware 
    (CPU Time was expensive and should not be shared for IO/Interrupts)

b.) The Lack of a performant Networkhardware 

(Modern Hardware does offload TCP Flow to the Adapter, uses Jumbo uses
Jumbo Frames and so on, so the main argument for generating the TCP
Overhead is gone.)

Nowadays you most often have Gigabit Ethernet Cards and can use Jumbo
Frames with TCP. This often results in higher throughput rates. 

On a High Performance Maschine NFS over TCP has the ability to have
somethling like Flow Control which helps when the Server is 1Gbit+ and
the Client only 100Mbit :) Or the other side around. 

For us Jumboframes and TCP was the way to go. 

> Hmm, care to share any references for this?  
> I'd be reaching for NFS over TCP in a long-haul type environment,
> but would run it over UDP otherwise.
> 
> -John
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-- 
Stefan Held                    VI has only 2 Modes:
obi unixkiste org              The first one is for beeping all the time,
FreeNode: foo_bar              the second destroys the text.
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