[mythtv-users] IOBOUND errors over NFS - fixed

[Rudy Zijlstra]

Kevin Kuphal wrote:

>Darryl Ross wrote:
>  
>
>>Hey All,
>>
>>I'm just posting this so that it'll end up in the archives in the hopes
>>that it might help someone else.
>>
>>My setup is as follows:
>> - SVN Trunk,
>> - Fedora 4 on all machines,
>> - Tuner-less master backend running on my file server (1.4Tb),
>> - Slave backend with 3 Twinhan MiniTer DVB tuners,
>> - Tuner-less combined frontend/backend.
>>
>>I've been struggling for about a week trying to fix a problem I've been
>>having with getting IOBOUND errors on the tuner machine when either
>>recording or watching livetv.
>>
>>After trying to chase down IRQ conflicts and all sorts of related
>>issues, the problem turned out to simply be that the e100 card on the
>>tuner machine was running in half-duplex mode.
>>
>>So, to fix it:
>>
>>ethtool -s eth0 speed 100 duplex full autoneg off
>>
>>I was getting IOBOUND errors within seconds of starting a recording, and
>> a two hour recording would end up being about 18Mb. After making that
>>change it is now up to 1.2Gb.
>>
>>Hopefully this will help someone!
>>
>>  
>>    
>>
>I added this to a new wiki page that hopefully others can fill in with 
>more suggestions:
>
>http://www.mythtv.org/wiki/index.php/Optimizing_Performance
>
>Kevin
>  
>
I strongly suggest you remove this mis-information from the wiki.

Considering how auto-negotiate is working, this "fix" is a solution 
waiting for a problem. It may hide the problem the OP is having, but is 
does NOT solve it.

If you force one side to full duplex 100, at reboot the other side will 
discover a 100 carrier without announcement (the auto nego information) 
and default to 100 half duplex. If you force 1 side of a link, you have 
to force *both* sides. On most consumer grade switches / bridges it is 
not possible to force the link. The only force that actually works as 
expected is 100 HALF duplex. All forcing of FULL duplex will lead to 
problems.

I suspect the OP has a different problem. What this problem is i cannot 
determine without more information. Several possibilities are:
- broken cable
- broken connector
- dying NIC (perhaps the one now being forced?)
- dying switch (the one the computer is connected to).
fix the broken component. That will really solve the problem in stead of 
hiding it for a while.

Regards,

Rudy

P.S. network management is part of my job for the network test setup we 
have at work.