PHP session management and load balancing

[cornish]

I need to distribute http requests across two server but also mating the php sessions at the same time.

I thought of using DNS round robin but realized that the PHP sessions would be out of sync when a user clicks through the site.

Google has come up with some answers

Balance and Ultra Monkey

Does any one use this software and is it right for my needs??

[nixnut]

perhaps haproxy is what you're looking for

[daemonflower]

I don't know any of these proxies, but I think maybe it is easier to beef up the script that does the round robin distribution a little: let it store the client IPs in an array and always route the same client to the same server. Should be done quickly and less pain than installing and learning a full blown proxy solution.

2 cents and all that

[kashani]

Rather than discuss software I'll discuss the two methods you can use.

1. sticky
In load balancer terminology sticky on a virtual IP refers to sticking a user to a particular real server. Your load balancer would need to keep track of the incoming user's IP and the server it was handed off to. Additionally you will set a time period for the stickiness to last, I'd suggest at least one hour.

2. db
Rather than worry about locking a user to a webserver, why not keep session data in one place, namely the db. I recommend a seperate db, sitename_session, and using innodb because session tends to be write intensive.

The limitations with locking a user to a webserver is that if the webserver dies you lose all session data when users shift to the other servers. The limitations with sessions on a db is now you have the overhead of a db. Between the two I like the db solution best, but most of the websites I've worked with recently already had a db so it was an easy choice.

kashani
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