I want to upgrade a webbsite to CMS 5 R1 SP3 because we have problems with the load balancing that is solved in that version. The webbsite is now running on version 5.1.422.256.
I know how to make the upgrade in CMS Manager BUT I can´t find any information about how the upgrade will affect the webbsite and the visitors during the upgrade!
We are running the webbsite on two load balanced servers, and my question is:
Can/should I do the upgrade when the webbsite is "on-line" for visitors/editors?
If so, what happens if a take one of the servers "off-line" and make the upgrade? Will the other one still work or is there anything in the database that make it stop working?
A workflow of how an upgrade should be done - needed backups, closing and so on - wouldn´t be wrong.
And what happens if something goes wrong? What back-out plan should I have.
Anyone having done this before?
I would do like this.
Normally whe first upgrade in a staging/test environment to see that everything works, then we run the installer on the live machines (with backups of course).
You'll get some downtime when the installer runs but you can add a app_offline.htm file to display a friendly message to the users.
Another more complex approach to get zero downtime would be (I still recommend testing on a staging/test site first and to have backups).
1. Create a copy of the database1. Bring site #1 offline2. Point #1 to the copied database3. Make sure it works and bring it online again4. Take #2 offline from the load balancer5. Upgrade #26. If everything works bring #2 online7. Bring #1 offline8. Point #1 to the new database (you can do it either before or after the upgrade)9. Run the upgrade10. If #1 also works bring it online
Note! Information entered during the upgrade will be lost. I haven't tested this approach myself but it should work perfectly fine.