With the release of Drupal 7 on January 5th of this year, there’s a new consideration in the mix for building Drupal sites. Is this old news? Yes. The new…news, however, is that you should begin asking this question: Should I go with Drupal 6 or Drupal 7?

Drupal Version 7?

When Drupal 7 was first released, I steered clear of using it for any of our projects at Accella. I knew that there were going to be some releases of the Drupal core with security fixes. I also knew that the module base was not going to be very large. The best part about Drupal is that you assemble sites. Drupal modules allow for rapid web development, potentially without programming.

If the Drupal modules you want to use for a project aren’t available in Drupal 7, development time on the project could easily be tripled. That’s not to say that the time to develop the project becomes abnormal, but rather, the time to develop the project is no longer shortened by using Drupal.

So Drupal Version 6 – right?

So, it seems that the answer to the question is Drupal 6. Even after all these months, is Drupal 6 still the version of Drupal you should use on your project? As of June 19th, there are 239, 862 reported installations of Drupal 6. This number comes from the usage statistics on the last four releases of Drupal 6: 6.19, 6.20, 6.21 and 6.22. These four releases range from August 11, 2010 to May 25, 2011. For Drupal 7, there are currently three releases out of alpha, beta, and release candidate stages that have usage statistics: 7.0, 7.1, and 7.2. As of June 19th, there are 36, 118 reported installations of Drupal 7. These three releases range from January 5, 2011 to May 25, 2011.

Out of the total reported installations (275, 980), 87% of the installations are Drupal 6. That’s a lot of people still using Drupal 6. That’s a lot of people who still need Drupal 6 support. That’s a lot of people who still need Drupal 6 modules developed. That’ s a lot of people still working on Drupal 6 modules and not working on Drupal 7 modules.

Now, it really seems like Drupal 6 is the answer to the question of which version of Drupal should I use. How quickly is Drupal 7 growing, though?

Over the first 25 weeks, almost 6 months, of 2011, Drupal 7 has grown at an average of 618 reported installations a week.  That’s a 2.2 average percent increase per week of reported installations since the 7.0 release of Drupal 7.  If this rate continues linearly, by the end of the year there will be around 52, 000 reported installations of Drupal for a total increase of around 232% since the initial Drupal 7.0 release.  That’s a lot of potential increase.  The number of reported installations of Drupal 7 has already grown by 130% since the beginning of the year.

Upgrade Path/Migration Route

The final consideration between Drupal 6 and Drupal 7 is the upgrade path or migration route. Upgrading across Drupal core versions, i.e. Drupal 5 to Drupal 6 or Drupal 6 to Drupal 7, is known to be a headache. The more contributed modules you use on your site, the more of a headache it is. Often, I find that the work estimate for starting the site with a clean installation of the new Drupal core version and migrating the data myself is the same or even less than the estimate to upgrade the site and fix everything that goes wrong.

So Which is it?

With this in mind, should you install Drupal 6 when the Drupalverse is moving toward Drupal 7? Once the scales shift in favor of Drupal 7, Drupal 6 support is likely to decline rapidly. Is that a position you want to be in? Should you take the risks now and the potentially slower development time associated with Drupal 7, so you don’t have to pay for a whole new site just to upgrade yours from Drupal 6 to Drupal 7 when Drupal 6 has fallen by the wayside?

Now, is the time to begin the balancing act of Drupal 6 and Drupal 7.  I hope the information presented here gives you a clearer picture of what’s going on with Drupal 6 and Drupal 7.  One thing I left out that you might want to examine is the changes in Drupal 6’s growth since the release of Drupal 7.  That information might give some sense of when the scales are going to shift from Drupal 6 to Drupal 7.

Drupal 7.3 and 7.4 were released today. Drupal 7 continues to grow.  To see if your site is ready to upgrade to Drupal 7, check out the Upgrade Status module.