Does firmware have to be identical on all drives?

[DIY_glenn]

Hi!

I'm about to set up my QNAP TS-453Be, but unfortunately discovered that one of my two Seagate ST4000VN000 pulled from my Windows Server (approx 2.5 years old) has a S.M.A.R.T error (End-to-End_error). The drive will be replaced by Seagate, with me having to cover shipping and any VAT/fees involved.
I believe both drives have firmware "SC60" if I remember correctly.

I now got hold of two old-stock ST4000VN000 for a very low price. Both are new in box, but one has SC43 firmware and the other SC44 (there's one year between them).
How big of a deal is this? Should firmware be identical? From SC43 to SC44 it's probably minor changes, but I mean from SC43 to SC60...?
I'll probably only use two drives, and since the replacement from Seagate also will be a used one, it's tempting to switch both drives for the two new ones.

I couldn't find a way to update the firmware, so what do I do now? I sent an email to Seagate if they are compatible, or if it is possible to get a firmware update for it.
What do I do? I'd like to get started, but I also want to avoid having to re-initialize the RAID.

I'm going for RAID0 (4+4TB) as my backup solution is more than good enough, and the data isn't crucial, so I'll try without redundancy this time around (until I can care to purchase 2x8+TB drives).

[dolbyman]

unless the firmware fixed a critical bug it does not matter .. you can mix different vendors without an issue so firmware certainly doesn't matter

on RAID0 a singe *blip* on one drive and you have to start over anyways , so as long as you are ok with the risk and rebuild times .. all good

[DIY_glenn]

unless the firmware fixed a critical bug it does not matter .. you can mix different vendors without an issue so firmware certainly doesn't matter

on RAID0 a singe *blip* on one drive and you have to start over anyways , so as long as you are ok with the risk and rebuild times .. all good

Thanks! I guess their drives is a constant work-in-progress, so probably not a big difference between the two.
Heh, how much of a "blip" are we talking about?
The data is backed up locally and through cloud storage, so I'm not afraid to lose anything, but yes - I do understand the risks (and somewhat stupidity) of using RAID0.

I suspect there are some larger differences between the SC43/SC44 and the SC60 drives I have, I'll have to check. The latter probably has a slightly different product code.

[DIY_glenn]

So I’ve gone ahead and set up my RAID.
I was considering RAID5 with the SC43 and SC44 drive + a SC60 drive. The latter had a slightly different product number (still ST4000VN000) so it might be “very” different from the first ones.
I’d like to do it, as I only add one drive, but get redundancy.
Although resyncing after failure typically takes a lot of time IMHO, and I’ve experienced a second drive failing only 1 hour after a full recovery.

The next option is RAID10 (if possible) but I’d be doubling the amount of drives for same storage and performance.

I trust these two unused drives more than mixing in a newer one that’s already been spinning for 2.5 years, and the one that’s going to be replaced by Seagate for a refurbished one.

All in all, redundancy is never backup, and I have a good backup solution.

I also like the possibility to add a SSD for containers/VMs and a separate 4TB for Time Machine backup.

Btw, is QNAP system data mirrored over all the drives?
Even if my RAID and time machine drive fails, it’s still on the SSD?