upstream backup

["Vitaliy Okulov" <vitaliy.okulov@xxxxxxxxx>]

Ошибка при указании параметра backup, в чем может быть проблема?

tcx# nginx -t
2008/10/01 18:10:12 [emerg] 45802#0: invalid parameter "backup" in /usr/local/etc/nginx/upstream.conf:2
2008/10/01 18:10:12 [emerg] 45802#0: the configuration file /usr/local/etc/nginx/nginx.conf test failed

upstream test {
    server   172.16.1.4 backup;
    server   172.16.1.5;
}

tcx# nginx -V
nginx version: nginx/0.6.32
configure arguments: --prefix=/usr/local/etc/nginx --with-cc-opt=-I /usr/local/include --with-ld-opt=-L /usr/local/lib --conf-path=/usr/local/etc/nginx/nginx.conf --sbin-path=/usr/local/sbin/nginx --pid-path=/var/run/nginx.pid --error-log-path=/var/log/nginx-error.log --user=www --group=www --http-client-body-temp-path=/var/tmp/nginx/client_body_temp --http-proxy-temp-path=/var/tmp/nginx/proxy_temp --http-fastcgi-temp-path=/var/tmp/nginx/fastcgi_temp --http-log-path=/var/log/nginx-access.log --with-http_addition_module --with-http_dav_module --with-http_flv_module --with-http_realip_module --with-http_ssl_module --with-http_stub_status_module --with-http_sub_module