[NCLUG] [Poll] VPS and web mangement hosting

[Sean Reifschneider]

On 02/17/2012 06:43 PM, Bob Proulx wrote:
> I am disappointed because it would have been interesting to know how
> much ram people desired, and how much disk they desired, bandwidth,

Unfortunately, most people don't really know the answers to many of these
questions.  Particularly RAM...  As some of you know, we do VPS and
dedicated hosting, so I'm somewhat familiar with this in the real world.

Most people are shopping entirely based on price.  For example, I've been
asked "How cheap are your virtuals?".  But, I've also found that most
people will seriously underestimate their RAM requirements.  It's a hard
question to answer, I'll admit...  Disc space is easy, you login, you do
"df -h", done.  Bandwidth is usually somewhat easy as well, if you are
already running the site you just look at your providers control panel and
off you go.

However, RAM is always in flux.  You login and run "free" and unless your
system is experiencing it's heaviest use right at that moment, you probably
only have the *MINIMUM* number, not the maximum...  Unless you have munin
running, you probably just don't know how much memory you need.

The biggest culprit is Apache.  You need to do the math: I want to be able
to handle X concurrent connections and each Apache instance uses YMB of
RAM, so X*Y is how much memory I need to handle that load.  Simple math,
but most people don't do it until it's too late.  :-)

It's not uncommon for Apache to use 25-50MB per connection, so if you want
to handle 50 connections (each site user may have multiple connections
remember, so this isn't a huge number), that's 1.25 to 2.5GB right there...

The default Ubuntu settings will set you up for, IIRC, 128 connections as
the limit.  So unless you tune this, you could be talking 3-6GB needed for
that.

There are many ways to reduce this footprint, but I won't go into that
here.

This is part of why our minimum virtual hosting offering is 2GB of RAM.
:-)

Sean