alert: ... pread() read only

[Nikolaos Milas]

Hello,

We are running a Joomla website loading a google map in an iframe (under 
NGINX) in the main (home) web page. This is the page mostly visited as 
it contains almost real-time data to be viewed by clients.

The system info:

Linux myserver.example.com 2.6.32-358.18.1.el6.x86_64 #1 SMP Wed Aug 28 
17:19:38 UTC 2013 x86_64
Database Version     5.5.34
Database Collation     utf8_general_ci
PHP Version     5.3.3
Web Server     nginx/1.4.2
WebServer to PHP Interface     fpm-fcgi
Joomla! Version     Joomla! 2.5.8 Stable [ Ember ] 8-November-2012 14:00 GMT
Joomla! Platform Version     Joomla Platform 11.4.0 Stable [ Brian 
Kernighan ] 03-Jan-2012 00:00 GMT

The problem is that there is a repeating error of the form (I have 
changed real host name and web root path, as well as client IP address):

2013/11/17 12:39:14 [alert] 20709#0: *9059 pread() read only 38605 of 
39107 from "/path/to/web/root/HTML/gmap/gmapv3_auto_el.html" while 
sending response to client, client: ::ffff:xxx.xxx.241.42, server: 
www.example.com, request: "GET /HTML/gmap/gmapv3_auto_el.html HTTP/1.1", 
host: "www.example.com"

I found here:

http://translate.google.com/translate?sl=ru&tl=en&js=n&prev=_t&hl=pt-PT&ie=UTF-8&u=http%3A%2F%2Fforum.nginx.org%2Fread.php%3F21%2C9856&act=url

...that this is probably related to the "open_file_cache" directive, and 
in fact I do use (based on advice found on the Internet):

    open_file_cache max=5000 inactive=30s;
    open_file_cache_valid 30s;
    open_file_cache_min_uses 2;
    open_file_cache_errors on;

Is there anything I could/should do to optimize system operation to 
avoid errors?

Should I disable open_file_cache or not? (I do not entirely understand 
its implications.)

How should we determine the directive benefits?

Note: The aim is to be able to serve a few thousand requests per sec at 
peak, while normal traffic is < 20 reqs/sec.

I appreciate your suggestions.

Regards,
Nick