hard-disk util% got higher on enabling aio for nginx-1.2.1

[shahzaib shahzaib]

Hello,

         I followed this post
http://stackoverflow.com/questions/11250798/best-file-system-for-serving-1gb-files-using-nginx-under-moderate-write-read-p
to optimize nginx for large static files i.e (flv,mp4) and enabled aio on
nginx config which you can see below, and after enabling aio, directio, and
output_buffers, i could notice(iostat -x -d 3) that cpu util% got higher
from 10.00 to 35.00 and svctime got reduced to 1.00 from 4.00. So i came to
the conclusion that after enabling these directives , the i/o util% starts
getting higher and svctime start getting reduced.

1.Can someone guide me if aio directive helps improving nginx flv stream,
if yes than why it is utilizing too much hard-disk?
2. Reducing the svctime(iostat -x -d 3) for i/o is a good thing or not ?


http {
    include       mime.types;
    default_type  application/octet-stream;
    client_body_buffer_size 128K;
    sendfile_max_chunk 128k;
    access_log off;
    sendfile        off;
    client_header_timeout  3m;
    client_body_timeout 3m;

server {
        listen  80;
        server_name  domain.com;
        client_max_body_size 800m;
        limit_rate 100k;


        location / {
            root   /var/www/html/content;
            index index.html index.htm index.php;

}
location ~ \.(flv|jpeg|jpg)$ {
                flv;
                root /var/www/html/content;
                aio on;
                directio 512;
                output_buffers 1 8m;
                expires 15d;
                valid_referers none blocked domain.com;
                if ($invalid_referer) {
                    return   403;
                }
                }


Best Regards.
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