I’m an old guy, whose been in Linux, off’n’on since 1997 or 1996, and not a professional.

Keep that in mind.

I now always recommend a pair of NVMe’s,

with swap on both,

with root mdadm mirrored RAID1 on both ( I’ve read that BTRFS “RAID1”, when 1 mirror is missing on boot, simply won’t permit you to boot, unless you get jiggy with the damn thing, telling it arbitrary stuff, to get it to allow that )

with /home mdadm mirrored RAID1

and use the extra space for whatever.

Use SATA for your backups.

I recommend using the fastest NVMe’s you can get, but biggest is more-important.

Samsung … what are they, EVO drives? go up to 2TB, iirc, and are reasonably cheap ( for people who can afford such things )…

This gives Linux’s mdadm RAID1 speed ( it does RAID0 for reads, RAID1 for writes ), AND it gives greater reliability.

I’ve been stung by incorrect partition space allocation sooo many times, that now I’d stick everything on as few partitions as is sane, but as OpenBSD recommends, some filesystems on separate partitions breaks some attack-methods ( partly by breaking hardlinks ).

The difference that access-speed & bandwidth do, for your OS, and especially swap, is stunning, so if you’ve got the funds, consider the Samsung PRO NVMe’s, instead of their EVO’s, but definitely get quality & quick NVMe’s, RAID1 'em up, and enjoy.

PS: I always do a prototype-install, now:

whole-device ( except swap, EFI, boot ), 1 partition, install everything I’m likely to want, of that OS, take a look at the filesystem use, for different parts of the root fs-tree, and then begin deciding what partition-sizes to be considering, using a 1.5x or 2x factor for expansion-space… ( different distros with /usr and /opt, especially ).

Then I repartition into the intended structure, & install in…

And, of course, I now expect to have to re-partition 1/2y later, as the things I’ve later found, & added, alter the ratios…

Obviously, if this weren’t just some random guy at home, LLVM would make much more sense, because then partitions could be resized/redistributed on-the-fly.

But for now, for a machine I only-sometimes use, it’s good enough.

Maybe this seems useful information?

I hope so…

( :

I would create an LVM and combine the two to get 3TB in one logical disk.

Os on the fastest drive, one large partition + efi partition unless you have a need for separate /boot.

I use /boot on ext4 and / on btrfs with /home being a separate subvolume.

/boot is ext4 because grub has issues booting to btrfs when using ubiquity auto installer. Why? I do not know.

I hate partitions. Moving and resizing partitions is not fun if you don’t correctly predict exactly the amount of space you need. If you really want the modularity, use btrfs subvolumes instead. IMPORTANT: While it is definitely feasible, ability to retain subvolumes might depend on the distro installer! Check before you commit to this approach!

Also, consider using LVM or multi-device btrfs to make the drives act as one filesystem. This means that you will never have to worry about where to place your files to balance the load, but it might make removing/replacing a drive in the future harder.

I would go with option 4. I have a 1TB NVMe with /boot, /, and /home. Then I have two 1TB SATA III SSDs, one is for games and the other music. It makes more “sense” to have / and /home on separate drives but I don’t recommend this personally because / doesn’t need a whole terabyte of storage so it’d just be wasted. Swap is optional (I don’t use it even on Gentoo). Me picking option 4 over 3 is just personal preference though. I like having /home smaller because it just holds basic stuff and then I have my 2 extra drives as bulk storage dedicated to something.