The best use case has been experimented with duplicating jail instances between two different physical servers.

The solution needs to be more scalable. I rate its scalability a five.

I think that scalability is quite good. We have approximately 100 users and the size of the volumes range from 20 terabytes to 100 terabytes. Our total volume is a little bit less than 500 terabytes. We have not found any bottleneck in our current configuration.

At this time, we don't plan on increasing our usage but it may change in a few years.

In terms of scalability, it's a little bit difficult as opposed to something like using similar types of systems. I've been trying to build one with Raspberry Pi and a bunch of hard drives, however, the scalability is a problem in the sense that, for example, I have five hard drives, and if I want to double the size, I would have to buy five new six-terabyte drives. You don't get any benefit by just replacing one of them due to the fact that it works on the basis of the smallest one only. I'd say the scalability is expensive if you really want to increase the size as you've got to replace all the hard drives.

FreeNAS is scalable. We use it on standalone servers, not clusters. 

It is scalable to an extent. However you cannot simply add more drives without reinstalling (at least as far as I can tell -- I could be wrong).

No issues encountered.

It scales pretty well. There are five engineers who use this solution.

The solution is scalable.