Plex

I was referring to the actual storage system. Unraid's funny JBOD vs some easy to use industry standard solutions. Not the overall OS with any dancing bears it displays, or doesn't. ☺️

If you're looking at the latter, I have no argument against installing something with easy to use interface etc. like Unraid.

Guides no, but there's good documentation. E.g. LVMRAID and ZFS. Here's some overview of ZFS.

For storage arrays, I would use ZFS over LVMRAID for a few reasons the most important being data integrity.

For the system drive, i.e. where the OS is installed, LVMRAID might be simpler to use. There's probably a wiki somewhere for installing Debian on ZFS but LVMRAID has been a Linux staple for a while and it's easy to install an OS onto. E.g. via the OS installers. You could install on LVM then after you're up and running, you can convert that to an LVMRAID with a single command and a second SSD.

The simplest possible scheme I can think of from setup perspective is to use the Debian installer to put your OS on LVM. Once Debian is running, install a second SSD, the same size or larger, then use LVM's lvconvert to convert to a RAID1. See "linear to raid1" in the LVMRAID man page (doc). Then for storage, install ZFS and create a zpool of the desired type from the available disks and throw your data on it.

Read the docs (RTFM), write down a planned list of steps, build the commands needed for each step from the docs (where commands are relevant), then try it on a machine without data.

Here's a sample command I've used to create one of my zpools:

sudo zpool create -f -o ashift=12 -o autotrim=on -O acltype=posixacl -O compression=lz4 -O dnodesize=auto -O normalization=formD -O relatime=on -O xattr=sa -O sync=disabled -O mountpoint=/media/storage-volume1 -O encryption=on raidz /dev/disk/by-id/ata-W /dev/disk/by-id/ata-X /dev/disk/by-id/usb-Y /dev/disk/by-id/usb-Z

It looks complicated but it's rather straightforward when you read the doc.