[mythtv-users] Re: Samba 3 better than NFS 3 for recording over Ethernet

Jarod Wilson jarod at wilsonet.com
Thu Dec 29 11:31:58 EST 2005

On Thursday 29 December 2005 04:44, Yeechang Lee wrote:
> Ryan Steffes wrote:
> > Hmm, I wonder if this may be related to why nfs apparently locks my
> > machine in heavy use.  It started when I switched to gigabit nics
> > and I was blaming the cards, until I realized I could do high data
> > transfers with the computer as long as I don't use nfs.
> Simon Lundell <simon.lundell at his.se> says:
> > I have had the same exact problem. The machine hardlocks, and a cold
> > = boot is necissary. I eventually changed nics to a 100Mbit in the
> > frontend.
> Might the two of you be using Marvell-based gigabit Ethernet cards
> and/or SysKonnect drivers?  After I moved from the built-in
> Intel-based 100Mbps Ethernet jack on my MythTV frontend/backend to the
> D-Link DGE-560T--a PCI Express 1x gigabit Ethernet card, for which I
> had to download SysKonnect's own version of sk98lin--I found that I
> could consistently crash the system hard by using dd or mv to max out
> the traffic to my RAID 5 file server (which remained stable, and has
> always had gigabit Ethernet), regardless of jumbo frames. I have not
> seen this issue while simultaneously recording and playing back HD
> streams, but might well do so once I start recording more than one HD
> stream at once. I look forward to the core Linux kernel's own sk98lin
> or skge drivers supporting my card, hopefully soon.

Hrm, I have a bit of experience with SK cards lately... I've found that while 
(at least some of) the SK cards have hardware tcp segmentation offload 
support, it doesn't work worth spit. In particular, this was on SysKonnect 
SK9Sxx PCI-X dual GbE cards, and the problems happen under high load. You 
might check if you have it on, and if so, turn it off, let the kernel do it 
instead. Could help...

Check with:
# ethtool -k ethX:
Offload parameters for ethX:
rx-checksumming: on
tx-checksumming: on
scatter-gather: on
tcp segmentation offload: on

Turn it off with:
# ethtool -K ethX tso off

Jarod Wilson
jarod at wilsonet.com
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