[mythtv-users] Re: Samba 3 better than NFS 3 for recording over Ethernet

Simon Lundell simon.lundell at his.se
Thu Dec 29 04:17:16 EST 2005


Ryan Steffes wrote:

>
>
> On 12/29/05, *Greg Oliver* <goliver at cistera.com 
> <mailto:goliver at cistera.com>> wrote:
>
>     Jumbo frames are your friend
>
>     On Wed, 2005-12-28 at 21:29 -0800, Jonathan Tidmore wrote:
>     > On 12/28/05, Mike Frisch <mfrisch at isurfer.ca
>     <mailto:mfrisch at isurfer.ca>> wrote:
>     >
>     >         The "tcp" option may not be necessary but I haven't
>     taken the
>     >         time to
>     >         benchmark between TCP and UDP.
>     >
>     >
>     > For gigabit ethernet, the nfs people recommend TCP.
>     >
>     > From the man page for nfs (5):
>     >
>     > WARNINGS
>     >        Using NFS over UDP on high-speed links such as Gigabit can
>     > cause silent data corruption.
>     >
>     >        The  problem  can  be  triggered at high loads, and is caused
>     > by problems in IP fragment reassembly. NFS
>     >        read and writes typically transmit UDP packets of 4 Kilobytes
>     > or more, which have to be broken  up  into
>     >        several  fragments  in  order  to  be sent over the Ethernet
>     > link, which limits packets to 1500 bytes by
>     >        default. This process happens at the IP network layer and is
>     > called fragmentation.
>     >
>     > They go into greater detail about this issue.  For info use 'man 5
>     > nfs'
>     >
>     >
>     > -J
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>
>
>
> Hmm, I wonder if this may be related to why nfs apparently locks my 
> machine in heavy use.  It started when I switched to gigabit nics and 
> I was blaming the cards, until I realized I could do high data 
> transfers with the computer as long as I don't use nfs.
>
> Ryan
>
>------------------------------------------------------------------------
>
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>  
>
I have had the same exact problem. The machine hardlocks, and a cold 
boot is necissary. I eventually changed nics to a 100Mbit in the frontend.

//Simon


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