[mythtv-users] NFS and remote backend

[Steven Adeff]

On Jan 11, 2008 10:40 AM, Steven Adeff <adeffs.mythtv at gmail.com> wrote:
> On Jan 11, 2008 10:25 AM, Brad DerManouelian <myth at dermanouelian.com> wrote:
> > 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.
>
> interesting, I'll have to try this. I don't record over NFS, just
> transfer files and stream to other frontends/laptops, but between the
> backend and the frontend I use it to transfer recordings I want to
> save, HD ones can be huge!
>
> crosses fingers as he ssh's into his home network from work....

Didn't seem to do much if anything. I changed the mount settings in
fstab, unmounted the existing mount and then remounted. I've got async
set in the nfs server's export line for the mount point.

12seconds for a 500MB file over ftp vs. 1:30 for the same file over NFS.

-- 
Steve
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