QuTS raid expansion options 3x16TB expanding with 3x18TB

[KartMan]

Hi all, 
I am using QuTS on TS-855. I have a raid 5 with 3x16TB and I am expanding with 3x18TB. What is my best option? Note I have 2 NVMEs for system pool. SATA SSDs and NVME for cache already. 
I am seeing the options for 'Create and Add new raid group" so that is 2 raid 5's with  a 3x18T raid and  3x16TB raid 5 with stripe. This makes another raid 5, but I am not sure if the end result is a raid 50. Is it? It says my capacity will end up at 59.99TB so it is utilizing the 18TB drives fully I think.
or 
Add to existing Raid Group. Here I can choose raid 5 or 6 or TP. Raid 5 gives 71.68TB ,  Raid 6 gives 56.25 TB.  
Are the extra 6TBs from the 3x18TB lost in these these cases?

Which is the best option to not waste the extra capacity of the 18TB drives and be fast? 
Will that raid 6 and raid 50 (?) be much faster than the raid 5 expansion? 
In my case with the different drives is raid 50 better than raid 6?

This is just a home NAS with my data, pics, vid, movies for remote use, AI for photo recognition, etc with future plans to host my own web site and small game etc.   


Thanks in advance.

[ed]

Based on your setup and requirements, here's a breakdown of your options:

Creating New RAID Groups:
Option 1: Creating two RAID 5 groups (3x18TB and 3x16TB) would indeed result in RAID 50. This configuration offers better performance and capacity utilization compared to RAID 6.
Option 2: By adding new RAID groups, you ensure that each group utilizes the full capacity of the larger 18TB drives, maximizing storage efficiency.
Adding to Existing RAID Group:
Choosing RAID 5 or 6 for the existing RAID group would result in combining the new 18TB drives with the existing 16TB drives. However, the additional capacity of the 18TB drives may not be fully utilized, potentially leading to wasted storage space.
RAID 5 would provide more storage capacity (71.68TB) compared to RAID 6 (56.25TB), but it's important to note that RAID 6 offers better data protection with dual parity.
In your case, considering the need for storage efficiency and performance, creating new RAID groups (Option 1) seems like the better choice. RAID 50 offers a balance between performance and redundancy, especially for a home NAS environment with multimedia files and remote access.

Regarding speed, RAID 50 typically offers better read and write performance compared to RAID 6, especially for sequential access patterns like media streaming. However, RAID 6 provides better data protection due to its dual parity scheme, which might be beneficial for hosting important data like photos and videos.