What downtime can I expect with a website migration?

In this article, we’ll be discussing downtime during a website migration and what’s to be expected.

All web designers and developers aim to keep downtime to an absolute minimum when migrating a website – that’s par for the course.

But what downtime is normal? Or rather what, as a rule of thumb, should be expected?

How long should you expect?

In an ideal world, the migration would go smoothly and there would next to no downtime. However, this is not always the case.

When discussing the migration of website, we generally say you should expect, as a worst case scenario, somewhere between two and four hours of downtime.

Why do you get downtime?

As you can imagine, there are a number of factors that can effect the downtime of a website migration.

Now, a lot of these factors can be minimised or eliminated through testing and using staging environments. So, we’ll be looking at the main external factors at play that are out of control.

Propagation of DNS settings

Propagation is how long it takes the change of domain’s DNS record to resolve externally. In simple terms, it’s how long before the world knows you’ve moved from one host, to the other.

Typically, and from experience, it can take up to four hours for DNS records to propagate, however, in some cases it can take up to 24 hours.

Purging of cached files

Note: this is more for when you’ve changed designs.

Cached files are files from a website stored on your web browser to help speed up the website on future visits. Usually cached files are images and code resources.

Now, as you can imagine, having files and images from the old site trying to load with your new site can cause some serious disruption.

It can take time for web browsers to realise the change and purge the old website files.

What you can do to minimise downtime or reduce the impact

Here’re our top tips to make sure your website migration goes as smoothly as possible:

1. Perform the migration ‘out of hours’.
2. Make sure you’ve tested the site in a staging environment on the new server before you change the DNS settings.
3. Put up a system status (i.e. popup) on your website alerting customers of potential downtime, prior to the migration.