When to update

Thanks for bringing up this discussion separately. The time I update depends on the site: traffic, importance, size of update, etc. I try to get most of my sleeping in around the 2:30 am range, so I do few upgrades at that time. ;-) There are some sites, however, where I'd schedule an update around a slower period.

Best practices dictate that all updates (at least major ones) be run on a development or staging site that has the same configuration as the production site. That can be run whenever (i.e. - office hours) and will alert you to any problems you may encounter upgrading the live site. If that passes with no issues, you can feel fairly certain that the live update will do the same. It's a good idea to put your site in maintenance mode when updating significant code (like Drupal core).

In practice, I must admit that I do most of my site updates during the day (even though I try for first thing in the morning or last thing in the evening when traffic has slowed). Those updates, however, are performed in a way that makes it easy for me to switch back to an older codebase within a few seconds if I get a WSOD or other issue that will take some time to diagnose. If you're not to the point of using the often dreaded "command line" for manipulating your Drupal site code, it's a good learning goal to have. It will make your life much easier. Perhaps that's a good topic for an upcoming meetup.

Seeing the magic that you and Andy can achieve with a few keystrokes is amazing! It would be great to have a meet-up where we talked about drush or command line manipulation. In the meantime, are there any books and/or websites that have a kind of crash course in this that you could recommend?

And thanks for the info about when you update. Our site doesn't have very heavy traffic, but I want to minimize the amount of people who could possibly see a site that's whacked out.

Important topic, thanks for raising it Trista, and excellent tips by Scott and Christopher.

Here's the official Drupal documentation on upgrading your site: http://drupal.org/upgrade - very good information, everyone should read this first.

I will only add one thing:

BACKUP, BACKUP, BACKUP your site before you update

Database backup

Particularly when you're running updates on a live production site. Not every core or contrib module update will alter your database, but many will, and although the chances of something going wrong are usually small, it can happen, particularly if you're using bleeding-edge -dev versions of modules. In those rare situations when you update and something gets hosed in your database, you will really appreciate the peace of mind that comes from having a minutes-old backup of your site's database you can roll back to.

There are several methods to back up your database. I've listed these roughly in order from easiest to hardest:

1. Install and use the wonderful backup and migrate module in your Drupal site. This is easy to use but also powerful, you can save DB backups to a directory on the server, an FTP location, have them sent by email, or download from the browser. Even better: you can set a regular backup schedule to take, say, daily backups automatically. Terrific peace of mind.
2. Use phpMyAdmin (often available from your host control panel) to export your entire database, and download it to your computer.
3. From the command line, use the drush sqldump command. This can be scheduled with cron for an alternative way to make scheduled unattended backups.
4. Also from the command line, use the mysqldump command
5. Also from the command line: 1,000s of other ways, take your pick.

Code backup

Since by definition bu upgrading you are replacing code on your site with new code, you should protect yourself in the rare case that the new code doesn't work, has a conflict with one of your modules, etc. So you should backup your existing code before overwriting it with the new version of Drupal you're upgrading to. Depending on how you roll (SFTP, SSH, command line) there are lots of different ways to do this (drush and unix symlinks can be very helpful here) so I'll just link to the Drupal docs page on backing up your site: http://drupal.org/node/22281)

Advanced - quick painless upgrades with instant roll-back

With a little bit of planning and command-line knowledge you can make core and module updates a quick painless experience, and be secure that you can revert both code and database changes in just a few minutes in case the upgrade goes south. I'd love to add this to the presentation on command-line skills in the near future.

For Drupal core, minor point-releases (e.g. 6.2, 6.3 etc) have historically been driven by security issues. Other bugfixes or performance improvements typically needed to wait (or languish) until there was an urgent security fix that needed to be pushed out. Recently there's been a proposal to put point releases on a monthly schedule, ensuring that non-security bugfixes get released at regular intervals.

For background on this, see the discussion here: http://groups.drupal.org/node/150854

In that thread it was pointed out that UPGRADE.TXT instructions have recently been improved to better describe how to do a minor-version update, clarifying that it's a pretty quick, painless operation. So I encourage everyone (including me) to read or re-read UPGRADE.TXT.