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

Rudy Zijlstra mythtv at edsons.demon.nl
Wed Jul 28 03:30:55 EDT 2004

Matt Perry wrote:

>I currently have 2 PVR-250s in my backend (P3 1GHz, 320MB ram, 27GB disk)
>and access all my Myth stuff via NFS mounts.
>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.
># 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.
>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...
Well, I have never run into that one. I am running a masterbackend with 
local storage. This storage is also accessed from 2 remote backends over 
nfs. The local storage is 3 250Gb disks in RAID5, without HW support.
filesystem: xfs. At the times the disks get hit pretty hard:
2 recordings (1 from master backend, one from slave backend) and viewing 
from 2 frontends at the same time. sofar no problems.
the masterbackend / mythtv nfs server is a PII 350MHz with 512Mb RAM.

1 PVR-250 datastream typically measures 5.5Mbit/sec, so if you have a 
100Mb network, your network should not be your problem. Unless you have 
network problems (check cables, check error counters, run network test 
program, etc... ) If you lose packets during transmission to the nfs 
server, this might cause your problem.

What is the config of your nfs server?



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