The Fine Print in Web Hosting: Resource Usage Limits

Implications for Webmasters and How to Plan Around It


The Fine Print in Web Hosting: Resource Usage Limits

by Christopher Heng, thesitewizard.com

When choosing a web host, we often examine a variety of criteria, look for reviews and personal recommendations, and even scrutinize in great detail the features offered by the prospective web hosts. In today's modern websites, however, this modus operandi fails to take into account something that plagues all growing sites but whose information cannot be found in the feature-list of any web host: resource usage limits.

Bandwidth and Disk Space are Seldom the Limiting Factor

Featured prominently in every web host's list of plans is the amount of disk space and traffic (bandwidth) your site is allowed. As a result, most people who look for a web host obsess over these items.

However, with more and more websites moving away from static pages to dynamically generated pages, the biggest limit that you will face is not your bandwidth or disk space, but what many web hosts vaguely classify as resource usage.

For those not familiar with the terminology, static pages are simple HTML web pages like most of what you see on thesitewizard.com. The web server merely displays what the pages contain with little extra work. Dynamically generated pages are what you get when you use blogging scripts like WordPress or content management systems like Drupal. The scripts assemble your web page from a variety of sources, such as your database and your templates, every time someone visits it.

The Real Resource Limits in Modern Web Hosting

There are three items usually subsumed under the general heading of "resources" where web hosts are concerned. Two of these apply to all websites, and the third only to script-driven websites.

  1. CPU Usage

    Whether a web page is static or dynamically constructed, the web server's CPU is used to obtain and deliver the web page to your visitors. When a page is dynamically created by a script, even more CPU cycles or resources are used, since the script has do a fair amount of processing to reconstruct your web page. It has to load the web template, obtain the data for that specific page from the database, execute the plugins or modules that you have installed, and finally assemble the page for delivery to the visitor.

    Since CPU time is a finite resource shared by all websites hosted on a particular web server, if any one website excessively uses the CPU, the other sites on that computer will not have an opportunity to deliver their pages in a timely fashion, and will appear either to be sluggish or non-responsive. As such, web hosts usually monitor the amount of CPU your site uses on shared web hosting plans, to prevent problems when a single website uses too much of the CPU time, adversely affecting the other websites on that server.

    If a site uses "too many CPU minutes" (in the parlance of some web hosts), the web host will typically ask the owner to upgrade to a more expensive plan or get a dedicated server, where the site is the only one on that machine.

  2. RAM Usage

    Most (if not all) web hosts tell you how much disk space has been allocated to your site. However, probably few shared web hosts tell you how much of the system RAM your site is allowed to use. Nonetheless, RAM usage is another limit that your site faces.

    RAM is the temporary memory that holds your site's scripts and their data while they execute. Unlike hard disk space, which web hosts can keep expanding by adding more hard disks using a variety of technologies, the maximum amount of RAM a machine can have is fixed. That measly amount of RAM is shared by all websites on that computer.

    This memory is needed by all programs that is run on the web server, including the server itself. If your scripts are huge, or they require a lot of RAM to execute, they will be competing in that limited pool of memory shared by all sites and all programs. As such, memory usage is another aspect of web hosting that web hosts monitor.

  3. Database Connections or MySQL Connections

    The data for dynamic websites is usually kept in special databases on the web host. A database server, such as the popular MySQL server, manages the database and provides the information requested by the site's scripts when they need it.

    Database servers have a limit on the number of connections they can accept at any one time. When too many requests for data are made simultaneously, they run out of resources and are unable to service those requests. This typically happens when your site receives a large amount of traffic, or when you use a script that is not very efficient (for example, it makes too many requests for every page it delivers), or both.

    I'm sure you have seen error messages like "Can't connect to MySQL server..." when you visited some sites before. The message means that a script on that site was unable to obtain certain information from the database that it needed to construct the web page. Very possibly, the database server was, in that instance, swamped with requests and could not service them.

Even Static Sites Face the Same Limits

Before you conclude that you are immune to the above limits if you run a static site, think again. While you may not have any scripts ramping up the CPU and RAM usage on your site, a surge of heavy traffic will still cause a CPU and RAM usage spike. Granted, that it takes a lot more traffic for a static site to hit a resource limit than a dynamically-driven site, you will hit that limit sooner or later if your site is popular.

Implications of the Resource Limits for Webmasters

Knowledge of these resource limits can help webmasters in at least two possible ways.

  1. Evaluating Web Hosts: The Web Hosting Gimmick

    If you visit the Budget Web Hosting pages on thefreecountry.com, you will undoubtedly have seen some web hosts providing a ridiculously huge amount of bandwidth for your website, with some even offering you unlimited data transfer.

    Now that you are aware of the "fine print" as mentioned above, you will probably also have realised that you will never be able to use up all of the bandwidth you are provided. Long before you even reach the amount you are supposedly allowed to use, your site will have hit its resource limits.

    Note that I am not telling you to avoid such web hosts. I use a few of them myself for some websites. Rather, I think that when you evaluate a web host to place your site, you should not give undue weight to bandwidth allocation, particularly if that bandwidth is excessively large. While the amount of bandwidth provided is always important, if you compare web hosts on that criterion alone, you are deluding yourself. Every shared web host has resource limits whether they state it or not. With those limits, your site will only grow so much on a shared host, whether you place it on hosts with an impossible bandwidth provision or on hosts with more sane bandwidth allowances.

  2. Planning Your Website: Static Vs Dynamic

    When you plan your website, always look at it in the long term. There are many benefits to using a blogging script or a content management system. In some cases, though, the dynamic site created by such a system is an overkill. If your site rarely changes and only has a set number of pages, such as is typical if you are only selling a particular product or a service, ask yourself if it is better off as a static site. As mentioned above, static sites run into the resource limits slower than dynamically created sites.

    Note that you should not decide to make your website static just for this reason alone. There are many other factors to consider, including those listed in my article on The Pros and Cons of Using an Online Blog Software or a Content Management System (CMS).

    If your site has to use a blogging software or a content management system, then you need to plan ahead for the time when you will no longer be able to use shared web hosting. In such situations, you will probably have to put your site on a virtual private server (VPS) or a dedicated server. The latter allows your site to use all the resources it needs since it will be the only one on the server (unless you choose to put other sites there). A VPS usually gives your site less resources to work with than a true dedicated server, but may be sufficient if your site is only just outgrowing shared hosting.

Conclusion

The features listed in a web host's plans ostensibly provide information about the disk space and bandwidth limits of every account. Modern websites, however, often encounter hidden limits not mentioned in the list provided by web hosts. More so than ever, these resource limits are proving to be the real limits that websites encounter today. Understanding these limits will help you better evaluate web hosts and plan for your website.

Copyright © 2007-2014 by Christopher Heng. All rights reserved.
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