Would these be overkill for a personal NAS at home?
It will be on the market soon. They will have to sell those binned parts somehow.
1) If you're a student, yes. Store less stuff. 1080 instead of 4k video won't kill you.
2) If you're a software engineer, factor in at least $200 of your time for each upgrade. Bigger drives mean you need to upgrade less often, so no, buying more is not overkill.
“Should I buy a lawn mower or pay someone to cut my lawn?” You factor in the cost of equipment, maintenance, and your time for both options, then figure out which works for your budget.
If your budget is zero, that also helps make the decisions easier.
If I always spent money to save myself time in line with how much I am professionaly worth (eg. paying for a lawn mower, never cooking for myself etc.) I think I would quickly be broke.
A two hour movie would be one hour of work. Probably worth it.
A trip to Disneyland was about 10 hours of work, but if I got there when the park opened I could do 16 hours of entertainment, so it was probably worth it.
Paying someone to mow the lawn was a few hours of work, but I could mow the lawn myself in an hour. So not worth it.
And so on.
There are things that I am willing to pay for even if it was cheaper to do it myself. There are also things that I'm willing to do myself even if it is cheaper to buy it.
You only do this calculation because you don't have any free time left so either you put it off until you can or you pay.
a) If I work harder and/or learn more, my salary and career trajectory will go up. There's an integrated increase over the rest of my life.
b) If I do consulting / startups / etc. on the side, what's that worth?
And you want to factor in risk, as well as not having bank account hit zero (even with risk). So if I'm unemployed (broadly speaking -- including planned unemployment like going to school), the expected value of my time hasn't changed, but the risk profile has, so my spending goes to as close to zero as I can bring it until I'm employed again.
For me personally, my 5TB x 2 RAID1 (ZFS really, so mirrored) configuration with 5TB usable is enough for my personal uses. If I need more space, I'll configure my ZFS with +2 HDDs for another pair worth of space+redundancy.
For my home bulk storage, I just have two normal 14TB drives and a nightly cron to rsync archive (new files only) from the primary to the backup. This gives me enough of a backup for both user error and hardware failure. It doesn't protect against a house-fire but that is ok.
I should maybe have considered BackBlaze but I can't believe they are going to last long if they continue offer flat-rates for multi-TB attached NAS.
Mirroring is for preventing hardware failures.
ZFS Snapshots are one protection against user-error. Backups are another.
It may be simpler to play with ZFS on VMs. The VM-disks will be small and inefficient, but "good enough" to prove whether or not the system works.
Not that I've tried any of this before. I happened to have an old computer lying around with ~4 small hard drives that I messed with to learn the ins-and-outs of ZFS the first time I used it. (Shuck hard drives, pull them out of laptops, etc. etc. Its not really that hard to get 4 hard drives to play with, especially if you ask your friends for ancient laptops with 200gb drives or something)
Of the many ways storage can get complex, I've found ZFS to be one of the most straightforward.
They're not exactly cheap, but I'm another one who went the Synology route. They slap a user-friendly UI ontop of linux mdraid and BTRFS, so you can RAID together a few drives, set up automatic BTRFS snapshots with retention rules (keep 12 hourly snapshots, 7 daily, 3 monthly, etc), set up disk scrubbing schedules etc all just by clicking around.
So it seems dizzying and unstable, but the dizzying bit is just nerd ego and hype, and the instability is also just nerd ego meets inevitability. (Now I think about it, it's a bit reminiscent of the abandoned "ABC shall be the ultimate XYZ" software you sometimes find online, and scriptkiddie mentality.)
ZFS is just a reasonable, mostly solid, somewhat idiosyncratic filesystem with nice features. Most of the failure noise online is from people who have no idea what they're doing; there are curiously (good-suspiciously) few public reports of commercial-scale data loss et al.
I've taken to using it as the root filesystem on a couple of Debian boxes. The Debian install instructions are both overblown and also almost hilariously broken, but that's a devops/sysadmin documentation failure, and not ZFS' fault. I spent a few years on Slackware, and have found the ZFS setup experience reminds me of that rock-solid-meets-flying-by-the-seat-of-ones-pants mentality.
The reason being that for larger drives, resilvering can take so long that secondary failures become probable or—in bad cases—even virtually guaranteed (This is the same probably the WD SMR drives had, but it exists even on normal drives if they get big enough).
For this reason, for modern large drives, most people recommend at least RAID6 (known as RAID-Z2 on ZFS), which means you have two drives worth of parity as compared to RAID5's single one.
Of course, this means that you need at least four drives for it to be worthwhile, and most people realistically end up going for around six disks, otherwise you are spending a lot of your total cost on parity.