Preparing for Large-scale Wordpress MU Usage

[CheezItMan]

I'm preparing to deploy a new Nginx server hosting Wordpress MU to our
school.  Each wordpress site will serve as a student ePortfolio.  I'm
concerned about when all 500 students hit the site and start editing at
the same time.  The particulars of my setup are below.  What can I
expect/do to prepare for the mass hit of users on my site?

I am running Wordpress Quick Cache, & apc (for php caching).


The Server:

OS:  Ubuntu Linux 12.04 LTS
Web server:  Nginx (naturally)
PHP:  php5-fpm
RAM 16 GB
CPUs:  2 CPUs with 4 cores each (total of 8 cores).

My nginx.conf file:

---

user www-data;
worker_processes 8;
pid /var/run/nginx.pid;

events {
    worker_connections 2048;
    # multi_accept on;
}

http {
    sendfile on;
    tcp_nopush on;
    tcp_nodelay on;
    server_tokens off;
    include mime.types;
    default_type  application/octet-stream;
    index index.php index.htm index.html redirect.php;

        client_max_body_size 512M;

    #Gzip
    gzip  on;
    gzip_vary on;
    gzip_proxied any;
    gzip_comp_level 6;
    gzip_buffers 64 32k;
    gzip_http_version 1.1;
    gzip_disable "MSIE [1-6].(?!.*SV1)";
    gzip_types text/plain text/css application/json
application/x-javascript text/xml
                        application/xml application/xml+rss
text/javascript;

    #FastCGI
    fastcgi_intercept_errors on;
    fastcgi_ignore_client_abort on;
    fastcgi_buffers 32 64k;
    fastcgi_buffer_size 256k;
    fastcgi_read_timeout 500;
    fastcgi_index  index.php;

    limit_req_zone $binary_remote_addr zone=one:10m rate=1r/s;

    ##
    # Virtual Host Configs
    ##

    include /etc/nginx/conf.d/*.conf;
    include /etc/nginx/sites-enabled/*;  #Our individual site vhost
server files will live here
}

---

My site file:

---
server {
    listen 80;

    server_name students.scisdragons.net;
    root /var/www/students.scisdragons.net;
    access_log /var/log/nginx/students.scisdragons.net.access.log;
    error_log /var/log/nginx/students.scisdragons.net.error.log;

        include global/wordpress-ms-subdir.conf;



        location ~* \.(js|css|png|jpg|jpeg|gif|ico)$ {
                expires 1y;
        log_not_found off;
        }

}

---

And my Wordpress Config file

---
location / {
        try_files $uri $uri/ /index.php?$args;
}


location /phpmyadmin {
               root /usr/share/;
               index index.php index.html index.htm;
               location ~ ^/phpmyadmin/(.+\.php)$ {
                        # Zero-day exploit defense.
                        #
http://forum.nginx.org/read.php?2,88845,page=3
                        # Won't work properly (404 error) if the file is
not stored on this server, which is entirely possible with
php-fpm/php-fcgi.
                        # Comment the 'try_files' line out if you set up
php-fpm/php-fcgi on another machine.  And then cross your fingers that
you won't get hacked.
                        try_files $uri =404;

                        fastcgi_split_path_info ^(.+\.php)(/.+)$;
                        include fastcgi_params;
                        fastcgi_index index.php;
                        fastcgi_param SCRIPT_FILENAME
$document_root$fastcgi_script_name;
                        #       fastcgi_intercept_errors on;
                        fastcgi_pass 127.0.0.1:9000;
               }
               location ~*
^/phpmyadmin/(.+\.(jpg|jpeg|gif|css|png|js|ico|html|xml|txt))$ {
                       root /usr/share/;
               }
        }
        location /phpMyAdmin {
               rewrite ^/* /phpmyadmin last;
        }


# Add trailing slash to */wp-admin requests.
rewrite /wp-admin$ $scheme://$host$uri/ permanent;

# Directives to send expires headers and turn off 404 error logging.
location ~* \.(js|css|png|jpg|jpeg|gif|ico|mov|mp4|avi|doc|docx|pdf)$ {
        expires 48h;
        log_not_found off;
}

# Pass uploaded files to wp-includes/ms-files.php.
rewrite /files/$ /index.php last;

# For multisite:  Use a caching plugin/script that creates symlinks to
the correct subdirectory structure to get some performance gains.
set $cachetest
"$document_root/wp-content/cache/ms-filemap/${host}${uri}";
if ($uri ~ /$) {
        set $cachetest "";
}
if (-f $cachetest) {
        # Rewrites the URI and stops rewrite processing so it doesn't
start over and attempt to pass it to the next rule.
        rewrite ^ /wp-content/cache/ms-filemap/${host}${uri} break;
}

if ($uri !~ wp-content/plugins) {
        rewrite /files/(.+)$ /wp-includes/ms-files.php?file=$1 last;
}

# Uncomment one of the lines below for the appropriate caching plugin
(if used).
# include global/wordpress-ms-subdir-wp-super-cache.conf;
# include global/wordpress-ms-subdir-w3-total-cache.conf;

# Rewrite multisite '.../wp-.*' and '.../*.php'.
if (!-e $request_filename) {
        rewrite ^/[_0-9a-zA-Z-]+(/wp-.*) $1 last;
        rewrite ^/[_0-9a-zA-Z-]+(/.*\.php)$ $1 last;
}

# Pass all .php files onto a php-fpm/php-fcgi server.
location ~ \.php$ {
        # Zero-day exploit defense.
        # http://forum.nginx.org/read.php?2,88845,page=3
        # Won't work properly (404 error) if the file is not stored on
this server, which is entirely possible with php-fpm/php-fcgi.
        # Comment the 'try_files' line out if you set up
php-fpm/php-fcgi on another machine.  And then cross your fingers that
you won't get hacked.
        try_files $uri =404;

        fastcgi_split_path_info ^(.+\.php)(/.+)$;
        include fastcgi_params;
        fastcgi_index index.php;
        fastcgi_param SCRIPT_FILENAME
$document_root$fastcgi_script_name;
#       fastcgi_intercept_errors on;
        fastcgi_pass 127.0.0.1:9000;
}

---

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,226786,226786#msg-226786