Looking for some guidance on which path to take for storage setup hosting my VMDKs. 

I currently have an NVME SSD which I wanted dedicated for my VMDKs domain share in Unraid. Originally I had planned on pointing the share to the specific cache setup for this purpose which is using that NVME and setting the cache pool to ONLY. I currently will backup the VMDKs off box separately. In order to prevent other shares form leveraging the NVME I would need to go through each share and ensure each one didn't default to this specific cache pool.
Recently I found that NVMEs can be added to the array. Would a better direction for my goal be to add the NVME to the array and under global share settings exclude that drive from the array and only include it for the domains share? If this approach was taken does the parity drive backup the NVME still? Would rather keep the option for btrfs raid 1 and a second NVME in the future instead of using the parity drive. 

Any guidance would be appreciated to ensure I started down the best path from the start.

Parity doesn't backup anything. Combined with the rest of the array it allows a missing disk to be rebuilt,  but Parity by itself contains no data. 

 

SSDs in the array can't be trimmed,  and can only be written at Parity speed. 

 

Put NVME in a pool not named cache, no share will use it unless you specify that pool for the share 

Great thank you for the guidance!