Hello!

It is not very clear to me if it is safe to install two parallel instances (and two databases) on the same shared server in different directories (ls1.name.com & ls2.name.com or name.com/ls1 & name.com/ls2).

The LimeSurvey Manual / General FAQs says that you need to update the session configuration:  Two LimeSurvey instances on same domain  without really explaining the reasons for that or consequences of not doing so.

Is the information in the Manual still relevant? Maybe someone should update the Manual page to clarify this subject.

These don't help:

• Multiple Instances On One Server  [multiple instances sharing the same files]
• Multiple instances of survey using same database

I am running two instances (LS3 and LS5) on the same VPS, different databases, different subdomains.

I did not make any changes to the session configuration, but I think I have set up two different sites in plesk and I think this is like having two different, indepenent accounts.

The sessions can be a problem, because the different session files could cause problems if there is the same session file for both instances. I think chances are pretty low, but if you have session 5456 from instance one and 5456 from instance 2, you will run into trouble of course.

Let's see if someone else, like for example @jelo has something more to say.

holch wrote:

I did not make any changes to the session configuration, but I think I have set up two different sites in plesk and I think this is like having two different, indepenent accounts.
 

Correct, subdomains had never problems cause each subdomain has a session cookie in the browser.

@imnetxiin
But you can install two or more instances in different folders under the same domain. The installer has improved and now creates a random session name (like all good php webtools). But it took years to get that issue recognized and then solved. Mostly the discussion ended like this:
forums.limesurvey.org/forum/development/...-default-sessionname

And it was this codeline, which fixed it.
github.com/LimeSurvey/LimeSurvey/blob/59...rController.php#L933


If you have old installations the config.php might use the default session name.
The most common issue when having two or more LimeSurvey instances on the same domain with the same session name is that you cannot be logged in more that one instance at the same time.

But when you install LimeSurvey these days, you no longer have to care about session names.

I think i have more than 20 instance on same server …

About session : it's just best to use different session name if you have account on same server.

BUT : if it's different domain name : no real issue separation between example.org and exemple.com session cookie, and separation between server1.example.org and server2.exemple.org too.

The only potential issue : have exemple.org/instance1 and exemple.org/instance2 : by default cookie name is the same for CRSF and session. Buit you can force cookie path to server1 and to server2 (or use different cookie name.