Firefox caching to NFS mounted home directories killing disk IO on file server

Donaldson Jeffrey jdonaldson at
Wed Nov 16 16:10:40 UTC 2011

Good Morning,

I'm having a big issue with Firefox caching. I have an Ubuntu Lucid LTSP 
server (fully patched) with 32 Thin Clients (Dell Optiplex GX270s). All 
of our student account home directories are stored on a file server and 
are nfs mounted on each LTSP server. The problem I'm having is that when 
the lab is full of students using Firefox, firefox seems to be 
constantly trying to cache pages to their home directories. This is 
driving up the disk IO on our file server dramatically which also causes 
load average on file server to spike and cpu going into wait states. 
This then trickles back down to the LTSP server also causing the load 
average to jump dramatically. I've been trying for a few days now to get 
Firefox to cache pages to /tmp locally for all users. I updated to 
Firefox 7, then edited the firefox.js in /etc/firefox/pref to include 
these lines -

pref("general.config.obscure_value", 0);   (supposed to tell FF not to 
worry about byteshift)
pref("general.config.filename", "firefox.cfg");

I then took a customized firefox.cfg file and placed it in 
/usr/lib/firefox-7.0.1. If I launch firefox, I get an error that it 
couldn't read the configuration file. So I downloaded the mozilla 13 
byteshift perl script and ran it on my cfg file. Then Firefox launches 
successfully, only problem is that it doesn't seem to be pulling or 
locking any of the preferences I set in the file (most importantly, 
browser.cache.parent_directory). Can anyone tell me what I'm doing 
wrong? Or is there a better way to set Firefox to cache locally for all 

Any help is appreciated!

Jeff Donaldson
Newark Charter School

Jeff Donaldson
Data Services Manager
Newark Charter School
(302) 369-2001 ext:425
jdonaldson at

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