VPS Server Stats -- how much RAM do I need?

I realize this topic has been covered a lot, but this should be quick and easy.

We've got a WPMU install with about 100 active blogs, and we're planning on growing to 250 blogs this year. Currently, we're hosted on a shared hosting plan and need to upgrade, but can't afford a dedicated server yet.

(Using about 4GB of disk space and about 30 GB Bandwith/month)

I have a friend who owns a hosting company who is willing to work with me to create a custom VPS with Nginx & memcached, and he's given me the following two options. He said that I can customize these choices (i.e. add more RAM) if necessary.

(Also, we're going to implement the W3 Total Cache with Amazon S3 or CloudFront CDN to offload theme & media files)

Option 1: Advanced Linux CentOS 5 - $99.50/mo or $272.85/quarter, or $960.00/year and will have 50GB of disk space and 3000Gb of data transfer per month, 4GB RAM.

Option 2: Premium Linux CentOS 5 - $59.50/mo or $164.85/quarter or $580/year and it will have 20GB of disk space and bandwidth 1000Gb data transfer, 2GB RAM.
Here's my question... If I go with the cheaper option for now, is 2GB RAM enough? Should I ask for 4GB or 8GB or more?

  • Barry
    • DEV MAN’s Mascot

    Have you had a look at Amazon EC2 Micro instances? I'm experimenting at the moment with an Ubuntu install, nginx and mysql - running exceptionally well so far and can be upgraded / moved to a larger slice at will.

    My estimated monthly cost is going to be about $30 - huge reduction from my Slicehost VPS (which is certainly going to be closed and transferred to another EC2 instance within the month).

  • SooBahkDo
    • Syntax Hero

    Hello All,

    I have the same questions about RAM needs on an installation with 150-300 active sites. What is an adequate amout of ram? I am unsure how WPMU uses it.

    How does the amount of memory being used per site on an WPMU install ( as reported by P Overview (lite) MU) relate to the amount of available ram on the server? Or does it?

    I too have established an Amazom EC2 account (1 year of free hosting and bandwidth for new accounts) and am currently trying to figure out all the configuration and setup variable to get a WPMU installation up and running.

    Barry, I would appreciate help with Amazon configuration and setup steps, advice, etc. that can shortcut my learning curve on Amazom EC2 and thus get our site running asap.

    Thanks in advance,
    Phil D

  • nickd32
    • The Incredible Code Injector

    @Barry - thanks for the info re:Amazon EC2

    The site says that micro instances provide only 613 MB of memory, which doesn't seem like enough to power WPMU.

    If I were going to use the VPS route, how much RAM should I ask for? Is 2GB enough, or should I request 4GB or 8GB?

  • nickd32
    • The Incredible Code Injector

    My server guy just gave me the following stats for the VPS we're testing:

    OS: Premium Linux CentOS 5
    Web server: nginx-stable-0.8.54
    PHP: php-fpm-5.2.17
    PHP accelerator: php-pecl-apc-3.1.6
    Cache: memcached-1.4.5
    Database: mysql-5.0.92
    WP Multisite 3.1
    W3TC Caching plugin

    Is there any other software we need in the stack to make this run as fast as possible?

  • eyecool
    • Design Lord, Child of Thor

    Servers are like plugins. You only want what you need. Everything else is just bloat.

    The only changes I'd made are:

    CentOS 5.5
    PHP 5.3.x, because PHP-FPM and APC are baked right in. No need to compile and configure. Much easier to upgrade in the future via yum. Runs as stable as stone.

    You've got APC. You don't need memcached. W3TC is another reason you don't need memcached.

    You'll be good to go for a long time.

    If and when traffic becomes insane, separate the services. Fire up a new VPS and move MySQL to it. That will get you down the road even further. Your DB should be good to go for a long while. So you just add more front end servers to handle requests. You can also add 1 or many dedicated memcached VPS to your infrastructure.

    The deal with any VPS is not to treat it as a mini-dedicated server. Big beefy VPS specs don't scale the same way an identically configured dedicated server would. It's most apparent with disk I/O.

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