Hello,

I am preparing to install LimeSurvey in production for high performance use, meaning, 100,00 monthly users of questionnaires, roughly 75 to 100 questions per questionnaire split over 10 to 20 pages, and expected session times of between 30 and 90 minutes per participant per questionnaire. I believe that this requires a solid configuration for performance (software-wise), availability, security (encryption of answers to questions).

However, I am unable to find instructions to install and configure LimeSurvey for high performance production purposes.

Some things I learned thus far:
- Increase size of sessions file (tmpfs)
- Encrypt answers to questions (can this be configured for the entire system as default?)
- Cache static assets in a CDN (does LimeSurvey support caching?)
- Send invitations and reminders to participants in small batches (does LimeSurvey support this or should this be done manually?)
- Minimize CSS and JS files (again, does LimeSurvey support this?)
- Increase the php.ini file to support greater memory

Are there any other software-related configurations that are relevant to consider?

Also, do you suggest a manual installation of LimeSurvey, or to use autoinstaller tools such as Installatron and Softaculous? In fact, do these auto-installers use any specific configurations or optimizations for the purpose of security, stability and performance?

Thanks for sharing your experiences!
 

Also, do you suggest a manual installation of LimeSurvey, or to use autoinstaller tools such as Installatron and Softaculous? In fact, do these auto-installers use any specific configurations or optimizations for the purpose of security, stability and performance?

No one really knows what they are doing, so I recommend to keep away from them. Limesurvey has a very simple installation GUI, so I think there is no real advantage of using one of these weird installation tools.

In terms of security, stability and performance, this is all up to you as the person who is responsible for the installation.

100k participants per month is nothing too extreme if you can spread them out over the month. E.g. 500 per work day.

However, I am unable to find instructions to install and configure LimeSurvey for high performance production purposes.

I think it is expected that someone who sets up a server for 100k respondents per month knows what they are doing. Also, the Limesurvey GmbH has probably no real interest in providing too much detail, as they also want to sell you their Limesurvey Pro SaaS offer.

Long questionnaires can be a concern, because it basically increases the time a session needs to be kept alive, thus more simultaneous responders at any given time.

I believe that this requires a solid configuration

I agree.

I am not an expert on server configuration but for a 100k per month installation with surveys of 30-90min I would consult someone who is well experienced in setting up servers in general (and ideally also in Limesurvey in specific). While it doesn't seem to be anything extreme to me, I think it will need to be something sold. It should work flawlessly or it will cause a lot of headaches.

- Encrypt answers to questions (can this be configured for the entire system as default?)

Do you mean to encrypt the answers in the database or do you mit SSL connection? Later I would definitely recommend, now encrypting all responses in the database will most probably have an impact on performance and I don't know if it is really that necessary.

Cache static assets in a CDN (does LimeSurvey support caching?)

I feel like this won't give you much increase of performance, not sure if it is worth the effort, but I might be wrong.

What makes me a little bit concerned is that you mention "Installatron and Softaculous", which usually is a sign for a rather low end hosting environment. Make sure that you throw a pretty solid server hardware at this.

Let's see what others have to say.

Hello holch,

Thank you for your reply! The reason I asked about these installation tools is that they are often also available on VPS and dedicated server configurations. I agree that I tend to want greater control when installing software, but it could have been possible that these installation-tools provide optimized configurations. That is why I asked that question.

At the moment, we are considering to use a dedicated server with these specifications:
- Intel Xeon 6-core CPU
- 16 GB RAM
- 512 GB NVMe storage
- 1 Gbps public connection
- CDN for static files

Do you think this would be suitable hardware to run LimeSurvey and the database on? In your opinion, could we also downgrade to a VPS, or would more dedicated resources be required?

but it could have been possible that these installation-tools provide optimized configurations.

I highly doubt it. Their job is not to improve, harden or optimize these software tools. Their job is it to provide one-click installations. I would rather expect them to "unoptimize" rather than "optimize" anything. For sure they have little to no knowledge about the hundreds of softwares that they provide for installation.

With 100k respondents per month, this machine will surely make your company some money or at least be very important for your companies success. I don't think I would go for a VPS but rather throw as much at it as it makes sense in terms of affordability. At the end of the day, you don't want to run into trouble during production. But as I said, I am not an expert on server configuration nor on Limesurvey installations for high traffic. But I certainly wouldn't cheap out with the expected load. I mean, it is not that you will be surprised by a high load, you already know that there will be quite a few respondents per month and your surveys aren't small either. 30-90min is quite long, so you probably also don't have the "normal" consumer surveys, because who is willing to fill out a 30-90min survey. So this must certainly be some B2B thing or at least some very specific target groups. Not the normal "panel" crowd I guess.

holch wrote:

 I don't think I would go for a VPS but rather throw as much at it as it makes sense in terms of affordability.
 

The decision between an VPS or an dedicated server is mostly about security and budget.
With a dedicated server you can run setups with fully encrypted storage, where even the datacenter staff cannot access it.
With virtual server there often is control software installed which e.g. allows to reset the root password or have other software running to control from outside.

A virtual server cost more in comparison to an dedicated server with the same specs.But you often got better hardware and more incentives providerwise to keep the Host of the VM running and in shape.

Depending on your webserver and php handler settings, you  check how many memory and cpu cycles is software is burning.

When you activate encryption on questions make sure you have a backup of the Keys.