What's the best setup to allow me to add drives and expand storage size as finances allow?

[IAmOrion]

Hi there, super new to "Proper" NAS's... I say "proper", because I currently have a single old 2TB hard drive connected to a Raspberry Pi using OpenMediaVault which is set up as a dead basic NAS - a simple network share that I can access from multiple computers.

Bear with me whilst I explain how I've come here... I've recently been digging into a better NAS solution that I can add to as finances allow. I'm super poor, and reading all these posts with people having 6 x 10TB drives or 6 x 3TB drives etc depresses me as I can only dream of starting like that!! ha. After lots of research I came across a video by "Tech By Matt" (https://www.youtube.com/watch?v=DpJViwtct5g). He is basically using an HP Z420 he's cobbled together. I started adding parts to my eBay basket / Amazon cart to start gauge costing - excluding storage at this point. During my days of searching I stumbled across a HP Z420 complete Workstation that worked out cheaper than trying to cobble one together! So I purchased, a HP Z420 (I believe V1 Motherboard), Xeon E5-1620 v2 3.70Ghz 4, 64GB ECC DDR3 (4x16GB) RAM, 600w PSU, HP Z420 Case, NVidia NVS310, for £200. No storage. I have 2 x 120GB Samsung 850 SSDs - which I read/heard I should set as the boot drive(s), with the second being a boot redundancy or something? (I guess I'll figure that out as I progress at the setup stage). I also have a 2.5Gbps NIC card.

Now comes the physical storage, I could only afford 2 x 4TB WD Re-certified hard drives. Actually they were re-certified Elements Desktop drives, and I've just pulled apart and got the drive out of. The 2 x 4TB cost me £110 total, compared to £220 had I of purchased brand new. (I've previously bought re-certified from WD and 5 years later the drive is still working great). Oh to be a popular YouTuber who just gets sent like 100TB storage as sponsorship eh!!

Anyways, that finally brings me to my actual question!... I want redundancy, so as I understand it, my 8TB of actual storage, would result in 4TB usable storage.
I want to be able to expand and grow my storage as time goes on and when I can eventually buy another 2x set of what ever storage I can afford at the time. Min 2 x 4TB, but ideally larger if poss. So how would I go about setting this up? What do I need to do that will allow me to increase my storage as time goes on whilst keep the redundancy feature etc. I swear when I was younger there was only RAID0 or RAID5. I'm sure the others existed of course, I'd just never heard of them! Jumping into this rabbit hole my brain is overwhelmed and overloaded with information and I'm so confused as to the best setup for my usage scenario and future expandability. Just FYI, I'm on the spectrum, and I really struggle with troves of information! It overwhelms/overloads me as I've mentioned.
Without coming across "lazy", I do a million times better following a guide for example, where someone is saying "get this, do that, this video walks through the easy setup"

Since the hardware is all "new to me" there's no data that needs saving or messing with etc, it's a new/fresh/clean setup. I just want to make sure I set it up correctly for my usage scenario

Any advice / help is very much appreciated. MTIA

 

[c77dk]

With two drives you want a mirror. And when finances allow, you can just add another mirror to the pool.
Boot mirror is a "nice to have". On my home NAS I just run a single disk, but on company servers I use mirrors (And always keep a backup of the config, so you can get the system back up)

Check the drives carefully to make sure they are CMR and not SMR.

 

[IAmOrion]

With two drives you want a mirror. And when finances allow, you can just add another mirror to the pool.
Boot mirror is a "nice to have". On my home NAS I just run a single disk, but on company servers I use mirrors (And always keep a backup of the config, so you can get the system back up)

Check the drives carefully to make sure they are CMR and not SMR.

FML! They're SMR - WD40EZAZ

Thank you for your reply, It's too late to return them now, and I won't be able to afford anything else for a good few months!

Can I make use of them for now somehow - will a raid 0 combine them into an 8TB NAS drive? And then when I can afford some more Drives (ensuring CMR this time!!), I would start a new pool of mirrored with the CMR drives, and can then expand that in the future. Effectively I'd have 1 8TB NAS Drive with no backup/redundancy (the 2 SMR drives) and then once I get CMR drives, I can create a redundant mirror pool that you mention.

Is "Mirror" mode a specific raid type, or will the option literally say "mirror mode"?

 

[noexpand]

With two drives you want a mirror. And when finances allow, you can just add another mirror to the pool.

But be aware: that does not increase the usable size of the pool. It just increases the redundancy.
If you want to increase the usable size of the pool you have to replace each drive of the pool with a bigger one.

 

[c77dk]

But be aware: that does not increase the usable size of the pool. It just increases the redundancy.
If you want to increase the usable size of the pool you have to replace each drive of the pool with a bigger one.

Not true - please read the docs

 

[IAmOrion]

But be aware: that does not increase the usable size of the pool. It just increases the redundancy.
If you want to increase the usable size of the pool you have to replace each drive of the pool with a bigger one.

Oh, that doesn't sound ideal! I'd, for example, to have 2 x 4TB already set up, for 4TB usable, and then at a later date add 2 more 4TB (or larger) to increase my pool size to 8TB usable with 8TB redundancy (or whatever best redundancy plan suits)

 

[IAmOrion]

Not true - please read the docs

Ah, ok, so when I add drives in the future (in pairs), would I "Expand Pool" ?
As an example, I create a mirrored pool using 2 x 4TB hard drives -- 4TB usable, 4TB redundancy. If I then add 2 more 4TB drives, I expand the pool, and it would then increase my pool to 8TB usable with 8TB redundancy?

When it comes to UPGRADING a drive in the mirror pool, can that be done easily? Would it have to be done in pairs - or at least, ideally done in pairs?
Eg: Remove 1 4TB drive, replace with 8TB - rebuild pool (or something similar) , then once complete, replace second 4TB with 8TB and repeat the process. Upping usable storage to 8TB upon completion?

I know I've read that if a drive fails, you can replace it with same or higher storage -- but does that increase the overall storage also?
If I have 2 x 4TB drives in mirror, and I replace ONE of those 4TB with an 8TB, would the usable storage increase from 4TB to 6TB (I'm assuming swapping in an 8TB would replace 4TB + have extra 4TB split into usable and redundancy again -- or do only complete drives get mirrored? So in other words, if I replaced ONE 4TB with an 8TB, my usable storage would REMAIN as 4TB until BOTH hard drives were replaced with larger?

Sorry for the gazillion questions!