[mythtv-users] Dual PVR250s + NFS = dropped frames

David myth at dgreaves.com
Wed Jul 28 04:38:05 EDT 2004

-----Original Message-----

>From: mythtv-users-bounces at mythtv.org
>[mailto:mythtv-users-bounces at mythtv.org] On Behalf Of Matt Perry
>Sent: Tuesday, July 27, 2004 7:34 PM
>To: mythtv-users at mythtv.org
>Subject: [mythtv-users] Dual PVR250s + NFS = dropped frames
>I currently have 2 PVR-250s in my backend (P3 1GHz, 320MB ram, 27GB disk)
>and access all my Myth stuff via NFS mounts.
it's been said before that 256Mb is a bare minimum for a single card 
backend - look here first

>I increased the NFS block size to 64k, but when I try to record two shows
>at once, I still get a pretty significant amount of dropped frames.
I'd drop the block size to 32k (you don't have much RAM)
what is your server doing?
if you max out your server whilst recording then you have problems.
I suffer from this 'cos my server has raid5 and if I copy nuvs to and 
from other workstations then it tops out on the raid5 daemon and the 
nfsds (athlon 1200 server)

There's no way of specifying to nfs that a particular client has a 
higher priority :(
I have wondered about nfs over tcp...

># cat /etc/fstab | grep mythtv
>stratosphere.internal.unshift.net:/var/local/mythtv /var/local/mythtv nfs
>rsize=65536,wsize=65536,soft,nfsvers=3 0 0
>I really can't figure out how to solve this problem, except for some sort
>of rip/rsync type of hack.
no need

>I'm also looking into channel bonding on both machines, to effectively get
>200Mbit worth of bandwidth.  I'd consider moving to Gigabit, except that
>requires all sorts of new and expensive equipment...
it's not a network bandwidth problem (or, more correctly, 100mbit is 
my frontend can record to nfs(1), read a stream from nfs(2) for local 
playback, read another stream from nfs(3) and send it out(4) to a remote 
frontend and not break a sweat.
(I am going to gigabit - but for the server and workstations, not the 
myth stuff - if you don't believe me

>Anyhow, just wondering if anyone's run into this problem, or even if
>someone who hasn't cares to chime in.
Install something like gkrellm and see what is going on.
I suspect your CPU or memory is maxing out (from nfs, not encoding)


More information about the mythtv-users mailing list