Which one of these configs would be the best

[Matibus08]

I have been theorising what would be the best configuration of hdd's for my needs. I can't decide between these three options:
1:

2:

3:

Could someone help me with which option would be the best for me?

I really want to keep all the data that's on these drives, speed is not an important factor for me it is mostly archiving on this pool. I have another pool for performance that will run VM's and fast storage. I am only at the place where this Nas is located in the weekends.

The white drives are Data
The red drives are parity
The Yellow Drive is a hot spare
The inner squares are Vdev's

Thanks in advance for all the help!

 

[Ericloewe]

Let's put succinct descriptions on those scenarios:

1. 2x 3-wide RAIDZ1 vdevs plus a hot spare
2. 1x 6-wide RAIDZ2 vdev plus a hot spare
3. 1x 7-wide RAIDZ2 vdev

Scenario 1 is weird, since it would perform a little better than a single vdev, but typically not enough better to be relevant. It's also not super reliable.
Scenario 2 is nonsense in most situations, a single 7-wide RAIDZ3 would provide the same storage with better reliability (the "spare" is always ready to go).
Scenario 3 is fine and safe.
Scenario 4 would be the sane variant of scenario 2, with a single 7-wide RAIDZ3 vdev, for better reliability than scenario 3, at the cost of some capacity.

Keep in mind that out of "20 TB", you'll get around 18 TB, which you won't want to fill past 80%, which leaves you some 14.5 TB usable.

 

[Matibus08]

Thank you I will probably go with Scenario 4 then. Is the reason that I don't want to fill it past 80% because of the performance decrease?

 

[Ericloewe]

In simple terms, yes. It's also a world of pain if you completely fill up the pool, but that applies to most systems out there.