Hey there,

Looking for some advice on what we should prioritise with our Lime Survey hosting solution between CPU (amount of cores e.g. 5, 6, 7, , Ram (in gb e.g. 9gb, 10gb, 11gb), Storage (SSD e.g. 40gb, 60gb, etc). Our main concern is wanting to make sure we can have a lot of concurrent database connections.

We typically have 3-4 surveys a week with 800 access requests per survey + potential for 1-2 additional surveys that have 1,000~ access requests.

Is it advisable that we prioritise CPU, Ram or Storage? Do you know how many cores / GB we should roughly aim to have for each one?

Any advice on this would be greatly appreciated!

P.S. How does Limesurvey handle concurrent database connections; is there some kind of limit we should be aware of, or is this all on the server side?

Thank you.

We typically have 3-4 surveys a week with 800 access requests per survey + potential for 1-2 additional surveys that have 1,000~ access requests.

What do you mean by access requests? Is there a time frame? 800 respondents per week?

The amount of RAM and CPU depends on the technology you use. What webserver, PHP version/webserver integration and database are used.
And CPU core can be very different in terms of performance.

The php sessions LimeSurvey is creating are big in size and are created when a respondent is hitting the survey.  As long as you use SSD you get enough I/O-Performance to not get into a bottleneck easy. The size of SSD depends seems not an issue at all.

If you use a hosting, you have to check what bandwidth you get.  Depending on your surveys content (a lot of images or videos). you already have an limiting factor in the bandwidth.

Before getting too much confused about everything, you can relax and just try to specify how many respondents you expect per hour. Check for the typical rushhours without invitations (13 and 17pm). 


 

Thank you, this is really helpful. Just so you know, I'm somewhat techy but I'm not part of the team putting this all together - they obviously have a lot more advanced knowledge than I do, but I'm just helping them out with some research on the side while they get this set up. Our anticipation on access rates is around 5,000 average (with a max of 7,500-8,000) per week.

These are obviously in waves, so not hitting the survey all at once, but do you have any recommendation on cores/RAM/Storage for this amount of responses?

We don't often use images/videos on surveys (and often host these on another site if we do).

Thanks for letting me know about Bandwidth however, I'm sure they've taken this into account but I'll pass this onto the tech team just in case.

but do you have any recommendation on cores/RAM/Storage for this amount of responses?

Who is your webserver administrator?  You have no information about what webserver  or PHP version you use. Depending on the amount of modules loaded by the webserver and the php interpreter, you can get very different allocation of RAM. If you want to serve a certain amount of concurrent requests, you let spawn additional webserver workers. That will occupied additional RAM.  Depending on the OS (Linux, Windows?) the RAM management is different.

Our anticipation on access rates is around 5,000 average (with a max of 7,500-8,000) per week.

Still unclear if you mean over all six surveys or per survey. 8000 per week is not much. 10 hours per day and only weekdays would mean 8000/50 hours = 160 visitors per hour.

If you have a default Linux OS distribution with a default webstack, I would start with 4 CPU cores and 8 RAM and a 40 GB SSD.  If you send invitations, you can control the flow to your surveys. If not, you might double to 8 CPU and 16 RAM. Without optimizing the configurations you might see little impact in throwing more resources at the stack.