[mythtv-users] NFS and remote backend

Brad DerManouelian myth at dermanouelian.com
Fri Jan 11 15:25:23 UTC 2008


On Jan 11, 2008, at 7:10 AM, Steven Adeff wrote:

> this isn't much help, but I noticed the same thing. NFS transfers are
> painfully slow and actually eat up a lot of "overhead" whereas FTP
> uses the full bandwidth and doesn't seem to eat up "overhead".
>
> I first noticed this when I switched my network to 1000bT. I used to
> transfer files between my master backend and my frontend (where my
> long term storage array is) via NFS but was noticing that when I did
> my recordings at that time would become choppy, the transfer speed was
> no faster than on my 100bT network and I couldn't watch an HD show on
> the frontend while transfering, it would just be choppy.  Then I tried
> FTP for the heck of it and it used the full network speed, did not
> affect recordings and allowed my frontend to play an HD show (with th
> obvious slowdown in the file transfer) without any problems.
>
> So there is definitely something wrong with the base setup of NFS
> somewhere. I couldn't figure out what, but at least I'm not the only
> that noticed this problem.

Not wrong, just optimized for transferring lots of little files, not  
the other way around.

> For now I've just been using FTP until someone can tell me why this is
> happening.

I followed the instructions here
http://www.mythtv.org/wiki/index.php/Optimizing_Performance#NFS_servers

set my options in /etc/fstab for my nfs mounts to:  
actimeo=0,intr,soft,rsize=16384,wsize=16384,nfsvers=3,tcp
I also had to specify async mode on the server side.

Now I don't have a problem recording a couple of HD streams while  
watching and commflagging any more.



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