[mythtv-users] mythtv + nfs = bad?

belcampo belcampo at zonnet.nl
Sat May 9 21:41:06 UTC 2009

Dale Pontius wrote:
> Alex Pearson wrote:
>> mythtv-users-bounces at mythtv.org wrote on 09/05/2009 19:56:46:
>>> From:
>>> David Brodbeck <gull at gull.us>
>>> To:
>>> Discussion about mythtv <mythtv-users at mythtv.org>
>>> Date:
>>> 09/05/2009 19:15
>>> Subject:
>>> Re: [mythtv-users] mythtv + nfs = bad?
>>> Sent by:
>>> mythtv-users-bounces at mythtv.org
>>> Alex Pearson wrote:
>>>> Hi All,
>>>>         I'm not sure if this will help anyone, but I found nfs 
>> unstable
>>>> on my box at home (which runs a number of nfs root'd servers as well 
>> as
>>>> mythtv storage), I resolved the issue by setting the clients to tcp 
>> and
>>>> also increasing the block size.  I now use the following mount 
>> options:
>>>>                 defaults,tcp,rsize=8192,wsize=8192 for general 
>> servers.
>>>>                 defaults,tcp,rsize=8192,wsize=8192,actimeo=0 for 
>> mythtv.
>>> If you're running nfsv3, I think 8192 may actually be *smaller* than the 
>>> default block size.  So you may have reduced it, not increased it.
>> Its interesting you say that, I didn't spend a lot of time looking 
>> into the block sizes (just dug in and had a play with them), but from 
>> the man page:
>>                       "If an rsize value is not specified, or if the 
>> specified rsize value is larger than the maximum that either  client  
>> or server can support, the client and server negotiate the largest 
>> rsize value that they can both support."
>> So you may well have a point!  Now I don't know whether I increased, 
>> or decreased, the block size!  Oh well... If its not broke (which it 
>> isn't now)
>>> I'm not going to argue with it if it fixed your problem, but I now 
>>> tend to stay away from rsize and wsize tweaks.  They were necessary 
>>> for older 
>>> NFS versions, but people have kept doing them as a sort of cargo cult 
>>> ritual even on newer versions.
>> I guess I'm a member of the cult ;-)  Cool, never been in a cult 
>> before....
> I'm running with:
> nfs4    rw,hard,intr,rsize=32768,wsize=32768,nosuid,nodev
> So the sizes can be bigger than 8192, and I guess I'm a member of the 
> cult, too.  Smaller cult even, because I'm running nfs4.
You can change default size with:
echo 1048576 > /proc/fs/nfsd/max_block_size
in your bootscripts on server size and your client, negociates according 
to 'less /proc/mounts'
server:/myth /smyth nfs 
0 0

> Prodded by this thread, I'm experimenting with rebuilding the kernel on 
> my backup server.  I tried applying the patch stuff, without luck.  The 
> patch won't apply directly, I suspect because the web page I downloaded 
> from did some whitespace damage.  I tried making the changes manually 
> and messed something up.  So I'm working on the theory that there is 
> some sort of fix in 2.6.29, and have copied svcsock.c and svc_xprt.c 
> from a client machine.  I've had to backtrack some changes out of 
> "svc_check_conn_limits", but finally have a clean compilation. Won't 
> know if it works until I make_modules_install, reboot and try using nfs 
> off of that machine, but at least I just got this far.
> More to come...
> Dale
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