Drive setup strategy questions

[BaNASa]

Hi all, I'm currently starting to build a NAS with a motherboard and processor that came out of my media streaming box when I upgraded them. It's an 8 bay hot swap + 4 bay box. It'll have a ASRock E3C226D2I motherboard with an Intel i3 4130T CPU.

I am planning on installing Seagate IronWolf Pro 16TB drives in it.

I'll be using it as a storage device to hold documents, major amounts of photos, video footage, and production music. I intend to access it when I travel, so I will be using a cloud addon. I also intend to have it sync select documents with all my devices.

My question is:

What setup should I use initially: Mirror or Z2? I want it to be solid, but flexible and easy to expand, should I need to gain more storage.

I know if I go Z2, I'll start with either 4 drives or 8 drives.

Obviously if I start with 2 drives, it'll be mirror of the 2, then I'd add mirrored pairs as I need.

What if I start with 4 drives and go mirrored: Stripe and mirror all 4 or stripe 2 mirrored pairs?

What if I start with 8 drives?

Thanks in advance for the input!

 

[Dice]

Obviously if I start with 2 drives, it'll be mirror of the 2, then I'd add mirrored pairs as I need.

This is a key insight.
(that guides all of your subsequent questions)

What if I start with 4 drives and go mirrored: Stripe and mirror all 4 or stripe 2 mirrored pairs?

You can start with 4 vdevs, and attach a mirroring drive to each vdev / drive.
That will also not grant you any redundancy and I doubt this is what you want.

The only reason to start with ~8 drives would to be to maximize space utilization by setting up a RaidZ2.
If you can't/don't want or feel like mustering the resources required, you could settle for fewer drives, with less space efficiency.

That's the logic that guided me about 6 years ago, which brought me to the conclusion to go with as many drives as I could possibly afford (and then some) to maximize space efficiency. I ended up with 7 drives.
The only downfall was/used to be the upgrade path. At the time it was really recommended to add same sized vdevs to a pool.
Thus, to upgrade, you'd have to add another 7 drives. I found my own "comfortable spending limits" were REALLY stretched at 5-6 drives, and could not handle 7 drives.
Should I've done it again, I would've opted for a managable "upgrade size" rather than the initial spending optimization, as I expected to at some point expand into a 2nd vdev, on my main pool.

These days, ZFS space allocation has changed, and is no longer as critical to have same sized vdevs in a pool. ("Balancing" is rather based on latency, which coincides with fill rate per vdev. Thus the fastest vdev will receive the data, and no "perfect stripe" where one vdev is overfilled and the other is partly empty. This clever setup means that vdevs balances out organically while at the same time provides the best user experience.)
I would still very much recommend to <aim> at the same number of drives in each vdev.

Generally it is more important to have a lot of free space on your pool, than it is match hdd speed/vdev width, to your overall performance.

A small comment on this part:

It's an 8 bay hot swap + 4 bay box.

I'd aim to have 1 HDD bay free, in case you'd need to make any drive replacements. It is favorable for resiliency during resilver to "add the new" before "removing the bad drive".

Good luck :)