Switching from a Media Drive to my first self-build NAS

I'm finally taking the leap from upgrading from a media drive sitting in my desktop PC to a self-build NAS. The parts are on their way and I have to figure out what to do when they actually arrive.

Current setup: Desktop PC with a single 20TB media drive (zfs, 15TB in use)

My knowledge: I use Linux as my daily driver, but I'm far from a power user. I can figure out and fix problems with online resources or the kind help of others like you

The goal: I want to move to a small NAS (2 additional 20TB drives are on their way). The system will have 32GB of DDR5 RAM. 1 disk parity for 40TB of usable storage

What will I use it for:

• Backup for Desktop PC
• Media server (Jellyfin)
• Arr stack
• (other small services int he future?)

My questions:

1. What OS should I use? The obvious answers being Unraid or TrueNAS. The 40TB of storage (1 disk parity) will likely be enough for a couple of years. So adding additional drives is not planned for some time.

2. How can I import the data from my current drive to the NAS? I am very new to the topic and my initial searches were not that helpful. With Unraid I should just be able to setup the first two disks and import the data from the other. I am unsure how to accomplish that with TrueNAS.

Some advice and tips would be great. Feel free to ask for more details if I forgot some crucial info.

Thanks for reading!