nginx better proxy cache configuration

nginx.conf

map $uri $store_uri {
    default $uri;
    '' '/index.html';
    '/' '/index.html';
}

server {
    listen       443 ssl spdy;
    server_name  www.it68.com.cn;
    ssl on;
    ssl_certificate /home/ssl/it68.crt;
    ssl_certificate_key /home/ssl/it68.pem;
    ssl_prefer_server_ciphers on;
    ssl_ciphers HIGH:!MD5:!aNULL:!EDH:!CAMELLIA:!PSK:!SRP;
    ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
    ssl_session_cache    shared:SSL:10m;
    ssl_session_timeout  10m;
    client_max_body_size 8m;


    location / {
        expires 60s;
        trim on;
        trim_js on;
        trim_css on;

        charset utf-8;

        default_type text/html;
        #index index.html;
        root /var/www/tmp/;
        error_page 404 = @fetch;
        error_page 403 = @fetch;

        subs_filter http://www.it68.com.cn https://www.it68.com.cn ir;
        #add_header 'Content-Encoding' 'gzip';
        gzip on;
        gzip_types text/plain application/xml;
        gzip_min_length 1000;
        gzip_proxied no-cache no-store private expired auth;
        etag on;

    }

    location @fetch {
        internal;
        proxy_ignore_headers   'Set-Cookie';

        proxy_hide_header      'X-Tumblr-Pixel';
        proxy_hide_header      'X-Tumblr-Pixel-0';
        proxy_hide_header      'X-Tumblr-Pixel-1';
        proxy_hide_header      'X-Tumblr-User';
        proxy_hide_header      'X-UA-Device';
        proxy_hide_header      'X-UA-Compatible';
        proxy_hide_header      'Link';
        proxy_hide_header      'P3P';
        proxy_hide_header      'CF-RAY';
        proxy_hide_header      'CF-Cache-Status';
        proxy_hide_header      'Date';

        proxy_set_header       'Cookie' __cfduid=d551f349d3baf701b7c8d2da2b48ffb6e1438576503;
        proxy_set_header       'Accept-Encoding' '';
        proxy_set_header       'User-Agent' 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/44.0.2403.107 Safari/537.36';

        proxy_set_header       'Host' 'www.it68.com.cn';
        proxy_pass             http://180.163.189.0:80;

        proxy_store  /var/www/tmp${store_uri};
        proxy_store_access  user:rw  group:rw  all:rw;

    }

}