I have a cluster set-up on AWS using Scalr.net. I am running Magento CE 1.7 on:
The intent is to store files caches and session caches on the memcached server. I have set up magento local.xml as so:
<session_save><![CDATA[memcache]]></session_save>
<session_save_path><![CDATA[tcp://XX.XX.XX.XX:11211?persistent=1&weight=2&timeout=10&retry_interval=10]]></session_save_path>
<session_cache_limiter><![CDATA[]]></session_cache_limiter>
<cache>
<backend>memcached</backend>
<slow_backend>database</slow_backend>
<slow_backend_store_data><![CDATA[]]></slow_backend_store_data>
<auto_refresh_fast_cache><![CDATA[]]></auto_refresh_fast_cache>
<lifetime>259200</lifetime>
<backend_options>
<servers>
<server>
<host><![CDATA[XX.XX.XX.XX]]></host>
<port><![CDATA[11211]]></port>
<persistent><![CDATA[0]]></persistent>
<weight><![CDATA[2]]></weight>
<timeout><![CDATA[10]]></timeout>
<retry_interval><![CDATA[10]]></retry_interval>
<status><![CDATA[1]]></status>
</server>
</servers>
<compression><![CDATA[0]]></compression>
</backend_options>
</cache>
But Memcached is not working. Here are my stats:
root@ec2-XX.XX.XX.XX:~# telnet ip-XX.XX.XX.XX 11211
Trying XX.XX.XX.XX...
Connected to ip-XX.XX.XX.XX.ec2.internal.
Escape character is '^]'.
stats
STAT pid 1086
STAT uptime 79364
STAT time 1352912987
STAT version 1.4.2
STAT pointer_size 64
STAT rusage_user 2.340000
STAT rusage_system 0.000000
STAT curr_connections 5
STAT total_connections 11
STAT connection_structures 6
STAT cmd_get 0
STAT cmd_set 0
STAT cmd_flush 0
STAT get_hits 0
STAT get_misses 0
STAT delete_misses 0
STAT delete_hits 0
STAT incr_misses 0
STAT incr_hits 0
STAT decr_misses 0
STAT decr_hits 0
STAT cas_misses 0
STAT cas_hits 0
STAT cas_badval 0
STAT bytes_read 28
STAT bytes_written 2194
STAT limit_maxbytes 67108864
STAT accepting_conns 1
STAT listen_disabled_num 0
STAT threads 4
STAT conn_yields 0
STAT bytes 0
STAT curr_items 0
STAT total_items 0
STAT evictions 0
END
Also, the site throws these errors:
a:4:{i:0;s:29:"cache_dir must be a directory";i:1;s:1097:"#0 /var/www/includes/src/Zend_Cache_Backend_File.php(154): Zend_Cache::throwException('cache_dir must ...')
#1 /var/www/includes/src/Zend_Cache_Backend_File.php(121): Zend_Cache_Backend_File->setCacheDir('')
#2 /var/www/includes/src/__default.php(60504): Zend_Cache_Backend_File->__construct(Array)
#3 /var/www/includes/src/__default.php(60445): Zend_Cache::_makeBackend('File', Array, true, true)
#4 /var/www/includes/src/Mage_Core_Model_Cache.php(124): Zend_Cache::factory('Varien_Cache_Co...', 'File', Array, Array, true, true, true)
#5 /var/www/includes/src/__default.php(23463): Mage_Core_Model_Cache->__construct(Array)
#6 /var/www/app/Mage.php(462): Mage_Core_Model_Config->getModelInstance('core/cache', Array)
#7 /var/www/includes/src/__default.php(20134): Mage::getModel('core/cache', Array)
#8 /var/www/includes/src/__default.php(20028): Mage_Core_Model_App->_initCache(Array)
#9 /var/www/includes/src/__default.php(20070): Mage_Core_Model_App->baseInit(Array)
#10 /var/www/app/Mage.php(683): Mage_Core_Model_App->run(Array)
#11 /var/www/index.php(87): Mage::run('', 'store')
#12 {main}";s:3:"url";s:1:"/";s:11:"script_name";s:10:"/index.php";}
if I include the following in backend options:
<cache_dir><![CDATA[]]></cache_dir>
<hashed_directory_level><![CDATA[]]></hashed_directory_level>
<hashed_directory_umask><![CDATA[]]></hashed_directory_umask>
<file_name_prefix><![CDATA[]]></file_name_prefix>
Your help will be greatly appreciated. Thanks.
My local.xml has a <memcache> section inside of <cache> and the <backend>Memcached</backend> is capitalized:
...
<cache>
<backend>Memcached</backend>
<slow_backend>database</slow_backend>
<backend_options>
...
</backend_options>
<memcached>
<servers>
<server>
<host><![CDATA[127.0.0.1]]></host>
<port><![CDATA[11211]]></port>
<persistent><![CDATA[0]]></persistent>
</server>
</servers>
<compression><![CDATA[0]]></compression>
<cache_dir><![CDATA[]]></cache_dir>
<hashed_directory_level><![CDATA[]]></hashed_directory_level>
<hashed_directory_umask><![CDATA[]]></hashed_directory_umask>
<file_name_prefix><![CDATA[]]></file_name_prefix>
</memcached>
</cache>
...
Also, you will want two instances of memcache running, i.e. use port 11211 for sessions and 11212 for cache. I have two files: /etc/memcache_1.conf and /etc/memcache_2.conf that setup these different instances. That way when you clear the cache it won't log out all of your users!