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Asked: 2026-05-14T07:42:58+00:00

I’m using lighttpd as webserver for php application server. The avg. load on this

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I’m using lighttpd as webserver for php application server. The avg. load on this server is about 2-3. MySQL database is separated to another server (it’s load ~0.4). How could I scale php application server?

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  1. Editorial Team

    In a few words, a solution, generally speaking, is to :

    • Have several PHP servers
    • Have another load-balancing server in front of those
      • If you have 3 PHP servers, then, this load-balancer will send 33% of the requests it receives on each PHP server.

    The load-balancing server can be some specialized hardware ; or a reverse-proxy, using Apache (see mod_proxy_balancer for example), nginx (see Load Balancing with Nginx, for example), varnish, …

    The most important problems you’ll generally face when using several PHP servers instead of ones are related to the filesystem : with several servers, each server has its own disks and filesystem.

    For example, if a user is randomly balanced on server 1 for one page, and server 2 for another page, you cannot use file-based sessions : the session will be created on server 1, but will not be found on server 2, later.

    In this specific case, you’ll have to use another mecanism to store sessions — store them in a database, or memcached, for example.

    Same things with images (uploaded by users, for example) : you’ll have to either :

    • Synchronise them between servers
    • Or use some kind of network-drive

    Edit after the comment : For the deployment, with several servers, I generally do exactly as I would with only one server.

    For more informations on the kind of process I often use, you can take a look at the answer I gave a while back on this question : Updating a web app without any downtime.

    The explanation given there is for one server, but to do the same thing on several servers, you can :

    • Upload the archive to each one of your servers
    • Extract it
    • And, at almost the same instant, switch the symlink on all servers
      • At worst, you’ll have 2 or 3 seconds of delay between each servers, which means 10 seconds if you have 5 servers ? It’s probably not a big problem 🙂

    (I’ve done this with up to 7 servers, for one application, and never had any problem)

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