[CentOS] NFS freeze when transmitting big files

Niki Kovacs contact at kikinovak.net
Tue Mar 30 11:27:04 UTC 2010


Hi,

I have one old spare PC, a PIII with 128 MB RAM, that I use as a spare 
file server. I have a headless CentOS 5 install on it, and a 2 terabyte 
external USB harddisk. The machine is in my basement (because it's quite 
loud), and I'm using what's called "CPL" here (Courant Porteur), which 
is basically Ethernet over 220V power lines. It's much slower than 
normally cabled Ethernet, but it works OK.

I setup an NFS server on this machine, with the big 2TB storage on the 
external disk. On the first floor, on my main PC, I setup a consistent 
mounting of the NFS shares in /etc/fstab, and it works.

Now here's the problem. Some of the files are quite big, usually movie 
files that can make up to 4 GB. More often than not, when I cut/paste 
such a file from my local harddisk to the server, it's quite slow 
(understandably, due to the slow CPL connection), but then the operation 
freezes in the middle, the cursor is unresponsive, even 
[Ctrl+Alt+Backspace] doesn't work, and I have to do a hard reboot.

Now I wonder what this phenomenon can be due to. Some strange bottleneck 
effect due to either lack of RAM to the server or the slow network or both?

Any ideas?

Niki


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