Hope everyone's off to a good weekend. I'd like to request advice and support as I navigate a slightly tricky situation with my homelab storage setup. Admittedly, I was a novice when I began my journey into this realm, and my understanding of VDevs, storage pools, and RAID arrays was quite basic at the time...mistakes were made.

I initially started with two mirrored 6TB drives, but for reasons now unclear to me, I decided to un-mirror them. Not my finest hour, but we live and learn. As I've read about data resiliency and learned more, I realize that I'm operating without a safety net and a single drive failure is going to be catastrophic.

Currently, my setup includes a single pool with three drives (12TB/6TB/6TB), operating without backup or resilience. It's a ticking time bomb, and I'm keen to address this issue urgently.

To give you a better picture, my server is a Dell tower that can accommodate two disks. It currently holds my Trusnas OS on an SSD, with two additional disks. I also have a 4-disk external SATA enclosure with one drive, giving me a total of six disk slots.

Here's my vision for an improved setup:

• Implementing a RAID array on my disks (RAID5 seems appealing, but I'm open to a simpler mirrored pool if that's advisable)
• Creating a local backup with a dedicated set of disks
• Ensuring future scalability, as my current usage is around 16TB out of the available 24TB, and I anticipate needing more space within the next couple of years.

The challenge I'm grappling with is how best to migrate the data from my existing three disks into a new storage pool. Ideally, I'd like to end up with a RAID5 array of 3x 18TB drives, providing 27TB of usable, resilient storage. I could then use a 16TB disk along with my existing 12TB drive as a standalone local backup, and phase out the 6TB drives, which have been running for 5+ years.

My initial thought is to create the 3x 18TB RAID5, migrate the data there, and then replace my current pool with the new one. Following that, I could remove the 2x 6TB drives, reformat the 12TB drive, add it to a new pool with the 16TB drive, and run a backup.

However, I'm unsure about how to add more disks in the future should I need to expand my storage beyond 27TB.

Any constructive feedback, suggestions for alternative approaches, or validation that I'm on the right track would be greatly appreciated. Thanks in advance for your time and expertise.