Horizontal Scaling – Come, scale away. Come, scale away. Come, scale away with me.![]( "candycane")
So, it’s almost the holidays, and your website, DIYCandyCanes.com, is getting ready for that annual sweet, spiraling gush of cane-curious web surfers. Or, maybe you’re the CIO of Happy Widgets, Inc. and your CEO has just buzzed your desk to announce the next generation of Happy Widgets (The Widgets With a Kick!). They are ready to ship and the PR office is readying a multi-channel advertising blitz that will lead to thundering throngs of happy Happy Widget seekers to your E-commerce web properties. Or maybe you’re some kind of nation-wide aeronautics and space administrative body, and your latest robo-rover, GravCat, just found a shallow pond of bona fide Martian protzoa.
The point is, everyone around you at your office is excited except you, you’re anxious. Anxious because you know your servers are about to be hit hard, and your strategic information architecture plan included a fast-track Horizontal Scaling Initiative and it better now work as planned (mostly because the Happy Widget CEO now knows where your desk is).
If this describes you, you’re well aware of Horizontal Scaling, its promise, its perils and its potential. If this isn’t you (or just not you yet), read on.
1. THE PROMISE – “Mo’ Boxes? Mo’ Better”
Nevermind wondering if the Galaxy Class ships represent the Mail Servers and the Miranda Class cruisers are the App Servers. The point is…More is Better!
Adding hardware to your server environment to increase capacity is horizontal scaling at its simplest.
If one server box for a task is good, two is better and three is even betterer (it’s a word, no matter what spell check says).
Sometimes referred to as ‘scaling out’, the parallel resources of added hardware should make your server environment more robust.
A good example of Horizontal Scaling is the appropriate number of additional disks into a RAID-5 storage array.
So add more, life gets better…simple, right? Well, be aware there are some perils.
2. THE PERILS – “Mo’ Boxes? Mo’ Problems”
When it comes to adding servers or other hardware, familiar questions arise: How much capacity will be enough? Will these servers need to be a permanent addition to the environment or are they a temporary measure to assist a short-term increase in load? How can we know for sure?
The old perils of Horizontal Scaling were forebodingly simple: doubling your server hardware resources used to be expensive, and even if you could afford more boxes, the planning and preparations to do so was time-consuming. Fortunately, these perils are a little less perilous thanks to an increase in powerful but commodity-priced hardware. In addition, the ability to deploy Virtualized server infrastructure has decreased costs somewhat over adding physical servers and sharply decreased the implementation time of horizontal scaling.
The new perils, however of Horizontal Scaling are simply forbidding: some tasks are not well-suited to the utilization of the parallel resources of Horizontal Scaling. How your servers perform their processeses is important.
If your application can be broken down into more modules, perhaps it has a three tier architecture – a database layer, a business logic layer and a presentation layer – then it can be spread across more servers.
If it cannot be separated like this, the benefits of Horizontal Scaling may not be achievable. In addition, some technologies, such as relational databases, were architected before Horizontal Scaling was ubiquitous.
Simply adding more database capacity will not give a performance increase.
3. THE POTENTIAL – “Mo’ Boxes? No Problem.”
It is not necessary for every additional server in a horizontally-scaled environment to have painted-on abs. Doesn’t hurt any, either.
As we can see, Horizontal Scaling used to be a logistical challenge, but has now risen to be more of an application layer issue.
Correctly answering the right questions of Horizontal Scaling can lead to successfully meeting the challenges of increased traffic and server loads.
Let these thoughts guide your careful Horizontal Scaling plan and let the candy-cane making commence! Or let the universe get smaller one tiny alien puddle of goo at a time.
Stay tuned for next week’s adventure: Vertical Scaling – or, let’s bolt an Edelbrock on your Ethernet.
Did you utilize horizontal scaling for the holiday shopping season? How did it work?
In case you missed it, click here to read How to Prepare Your Website For the Holiday Rush- Part 1 of 3.
