Let me preface my complaint by saying that I really like unraid and it perfectly fits into my use cases (personal/home use).
I never really like the idea of raid, splitting (or duplicating) you data over different disks, it just makes me uncomfortable.
I like the control and and flexibility unraid gives me. For example I don't split my shares over disks. I like to know which disk has what data. Since I have a small setup setup, this works for me.
I wasn't really using my cache drive for cache purposes either, I don't necessarily need the extra speed most of the time. But I have my system and appdata on it as that's the default option and it makes sense.
I use my cache drive (SSD) mainly to store disk images for my VMs. As you know it has great impact if you use an ssd as the system disk for an OS.
Now the other day I wanted to add a second SSD as a second cache drive, only to find out that I will have to reformat my current cache as btrfs and pool it with the new drive in a raid configuration.
I have no use for this. I just wanted to add a second drive for my VMs, nothing else. Why isn't this an option? Or maybe an option to auto mount a disk without being part of the array or cache pool.