cakephp的环境配置问题

新手求高手指导，目前在做项目，一天都没有搞定，很急。
环境：Linux(el7)+nginx(1.6.2)+mysql(5.6.23)+php(5.4.39)+cakephp(2.6.0)
web环境本身没有问题，访问http://172.16.3.91：8080/cake报错：
Warning: _cake_core_ cache was unable to write 'cake_dev_zh-cn' to File cache in /usr/share/nginx/dataCenter/lib/Cake/Cache/Cache.php on line 323

Warning: /usr/share/nginx/dataCenter/app/tmp/cache/persistent/ is not writable in /usr/share/nginx/dataCenter/lib/Cake/Cache/Engine/FileEngine.php on line 385

Fatal error: Uncaught exception 'CacheException' with message 'Cache engine _cake_core_ is not properly configured.' in /usr/share/nginx/dataCenter/lib/Cake/Cache/Cache.php:181 Stack trace: #0 /usr/share/nginx/dataCenter/lib/Cake/Cache/Cache.php(151): Cache::_buildEngine('_cake_core_') #1 /usr/share/nginx/dataCenter/app/Config/core.php(374): Cache::config('_cake_core_', Array) #2 /usr/share/nginx/dataCenter/lib/Cake/Core/Configure.php(72): include('/usr/share/ngin...') #3 /usr/share/nginx/dataCenter/lib/Cake/bootstrap.php(175): Configure::bootstrap(true) #4 /usr/share/nginx/dataCenter/app/webroot/index.php(100): include('/usr/share/ngin...') #5 {main} thrown in /usr/share/nginx/dataCenter/lib/Cake/Cache/Cache.php on line 181

1. 已经确认tmp目录上级和下面的子目录全部都设置了777权限；
2. cakephp（从官方网站下载的）除了修改了数据库配置外，其他的配置项没有动；
3. nginx.conf（参考官方文档设置的rewrite）
# For more information on configuration, see:
# * Official English Documentation: http://nginx.org/en/docs/
# * Official Russian Documentation: http://nginx.org/ru/docs/

user nobody;
worker_processes 1;

error_log /var/log/nginx/error.log info;
#error_log /var/log/nginx/error.log notice;
#error_log /var/log/nginx/error.log info;

pid /run/nginx.pid;

worker_rlimit_nofile 65535;
events {
use epoll;
worker_connections 4096;
}


http {
include /etc/nginx/mime.types;
default_type application/octet-stream;

log_format main '$remote_addr - $remote_user [$time_local] "$request" '
'$status $body_bytes_sent "$http_referer" '
'"$http_user_agent" "$http_x_forwarded_for"';

access_log /var/log/nginx/access.log main;

sendfile on;
#tcp_nopush on;

root /usr/share/nginx/html;
#单位：秒
keepalive_timeout 100;
#keepalive_timeout 1000;

#gzip on;

index index.html index.htm;
#uwsgi_buffering off;
#uwsgi_max_temp_file_size 64m;
# Load modular configuration files from the /etc/nginx/conf.d directory.
# See http://nginx.org/en/docs/ngx_core_module.html#include
# for more information.
include /etc/nginx/conf.d/*.conf;

server {
listen 8080;
#server_name localhost;
server_name 172.16.3.91 shuju.baijie;
rewrite 301 http://172.16.3.91:8080$request_uri permanent;

root /usr/share/nginx/dataCenter/app/webroot;
index index.php index.html index.htm;

#charset koi8-r;
charset utf-8;

access_log /var/log/nginx/dataCenter.access.log;
error_log /var/log/nginx/dataCenter.error.log;

# Load configuration files for the default server block.
include /etc/nginx/default.d/*.conf;

location / {
try_files $uri $uri/ /index.php?$args;
if (-e $request_filename) { #文件或目录存在
break;
}
if (!-e $request_filename) { #文件或目录不存在
rewrite ^/(.+)$ /index.php?url=$1 last;
break;
}
}
location ~ /\.ht { #禁止.htaccess
deny all;
}

location ~ \.php$ {
try_files $uri =404;
#这里指定了fastcgi进程侦听的端口,nginx就是通过这里与php交互的
fastcgi_pass 127.0.0.1:9000;
fastcgi_index index.php;
fastcgi_param SCRIPT_FILENAME $document_root/$fastcgi_script_name;
include fastcgi_params;
}
# redirect server error pages to the static page /40x.html
#
error_page 404 /404.html;
location = /40x.html {
}

# redirect server error pages to the static page /50x.html
#
error_page 500 502 503 504 /50x.html;
location = /50x.html {
}
}

server {
listen 8081;
#server_name localhost;
server_name 172.16.3.91 shuju.baijie;
root /usr/share/nginx/mytest;
index index.php index.html index.htm;

#charset koi8-r;
charset utf-8;

access_log /var/log/nginx/mytest.access.log;
error_log /var/log/nginx/mytest.error.log;

# Load configuration files for the default server block.
include /etc/nginx/default.d/*.conf;

location /phpmyadmin/ {
index index.php;
}
location ~ \.php$ {
#这里指定了fastcgi进程侦听的端口,nginx就是通过这里与php交互的
fastcgi_pass 127.0.0.1:9000;
fastcgi_index index.php;
fastcgi_param SCRIPT_FILENAME $document_root/$fastcgi_script_name;
include fastcgi_params;
}
}
}

回复讨论(解决方案)

Warning: /usr/share/nginx/dataCenter/app/tmp/cache/persistent/ is not writable in /usr/share/nginx/dataCenter/lib/Cake/Cache/Engine/FileEngine.php on line 385
已经明确的表示说
/usr/share/nginx/dataCenter/app/tmp/cache/persistent/ 不可写
这是个目录，而写缓存应该是文件名吧

谢谢 xuzuning 的回复。
persistent确实应该是目录的，不是文件，问题应该不在这里：
383 if ($this->_init && !($dir->isDir() && $dir->isWritable())) {
384 $this->_init = false;
385 trigger_error(__d('cake_dev', '%s is not writable', $this->settings['path']), E_USER_WARNING);
386 return false;
387 }

求各位牛人关注！

找到原因了，我的php.ini中配置cgi.force_redirect原来使用的是默认值（默认打开），设置cgi.force_redirect = 0将该配置关闭后，重启nginx和php-fpm就能正确获取writeable的值了。看php.ini中该配置项的注释，当打开时，php以安全的方式运行在web服务中。