Different Jira Versions Accessing the Same Database

[Jeff Shepherd]

If I have a load balancer on the front end and a shared database on the back end, is it possible to have different versions of Jira in between?

This would be the same major version. For example one server with Jira 8.8 and another with 8.12

[Nic Brough -Adaptavist-]

No, absolutely not.

8.8 and 8.12 have different databases.  If you connected the 8.12 to the database, it would upgrade it and the 8.8 instance would stop working.  However, you would not be able to do that at all, as Jira will only allow you to connect one Jira to a database, any second instance would detect the first already connected and simply shut down.  If the 8.12 were be allowed to upgrade the data, you'll then find 8.8 can not start against it, and there's no way to downgrade.

If you move to DC, you can, and should, have several nodes connecting to a single database.  The nodes all need to be on a similar, but not identical release (so 8.8 and 8.12 nodes still will not work, but 8.8.1 and 8.8.3 nodes will co-exist, although that is mainly to support the zero-downtime upgrade feature, not a standard operating model)

[Niranjan]

Hi,

Are you referring to different versions on different DC nodes connecting to the same database? 

[Florian]

Hi Jeff. Our installation is not that large that we need a load balancer. However we are thinking of moving to the data center edition.

As I understand one of the main advantages of data center is that you can do upgrades without downtime (https://www.atlassian.com/enterprise/data-center/jira). In my imagination this means you can upgrade one leg while the other one is still on the ground. Then you make a little jump before upgrading the other leg. I don’t know what happens in the (short) period where both legs are running different versions. Probably only one might be active while the other one is more or less useless. But with a data center license you can alway start a third or even a fourth instance so that you will not run out of resources. 

Let me know your experiences. As I said above we might want to switch to data center when Jira will become part of our critical infrastructure. Therefore I am interested in this topic. 

[Jeff Shepherd]

@Niranjan : Yes, this would be two (or more) Datacenter nodes connecting to the same database

@Florian : Yes, the idea is we keep continuous uptime while we add new updated node.

My thought is this: If the load balancer directs someone to the Jira 8.8 version, they would get an 8.8 experience. If a different user is directed to the Jira 8.12 node, they would get the 8.12 experience. Not that we would want to keep things that way forever, but if there are issues with the 8.12 upgrade we could always remove that node and continue with 8.8.

Another way of thinking of it is this: is the Jira 8.12 version of the database backwards-compatible with 8.8? I can imagine the upgrade from, say, Jira 7 to Jira 8 could make changes/updates to the database that make a return to 7 impossible. But I would hope all versions of Jira 8.x play nicely with one another.

[Niranjan]

Hi @Jeff Shepherd ,

I would not recommend running different versions as there may be other version specific factors like jira-config properties and config file changes. It is always better to run all the versions of your DC nodes on the same version.

PFB the article for upgrading DC JIRA with zero downtime

https://confluence.atlassian.com/adminjiraserver/upgrading-jira-data-center-with-zero-downtime-938846953.html