Sessions Failover with PHP-memcache against memcached

Question

Colleagues!

I\'m running php 5.3 (5.3.8) with memcache (2.2.6) client library (http://pecl.php.net/package/memcache) to deal with memcached server. My goal is to have f

Answer 1

I would like to thank everybody who participated this question, the answer is the following: in reality memcache (not memcached) as session handler supports comma separated servers as the session.save_path, moreover it supports failover. The error mentioned above Session start failed. Original message: session_start(): Server 10.0.10.111 (tcp 11211) failed with: Connection refused (111) had only 8th (Notice) level. In fact engine just informs you about the fact that one of the servers is unavailable (which is logical, as otherwise how will you know?) and then successfully connects to the second server and using it.

So all of the misunderstanding has been caused by weak documentation, memcache/memcached confusions and paranoid (E_ALL) settings of my custom error handler. In the meantime the issue has been resolved by ignoring notices referring to error Connection refused (111) in the session establishing context

Answer 2

You must change the hash strategy

Change your config to

memcache.hash_strategy  consistent

When you make the hash strategy to consistent memcache copies the data across multiple servers. If one of the servers is down, it retries to copy it on the next request.

Answer 3

Use the Memcached extension. Note that there are two memcache plugins for PHP. One is called Memcache, the other is called Memcached. Yes, that's confusing, but true anyway.

The Memcache plugin supports those complex URL's you're using, with the protocol identifier (tcp) and the parameters (persistency and so on), while the Memcached plugin supports connection pools.

The documentation you're mentioning in the comments above (http://www.php.net/manual/en/memcached.sessions.php) is about the Memcached extension, not about Memcache.

Update: Some interesting read: https://serverfault.com/questions/164350/can-a-pool-of-memcache-daemons-be-used-to-share-sessions-more-efficiently