No, there is no white list of acceptable replacements for storage disks held in firmware.
Apple doesn't make their own drives. Hard drives are made for Apple by Toshiba and Seagate, and the supplied drives are not 'custom built': they just meet a certain spec.
I've replaced the hard drive on hundreds of Macs and never had a problem of this sort.
You say that ...
The problem was coming from the SATA cable. Replacing it solved the
The failure was difficult to diagnose because intermittent.
Beware of the cable length. One MacBook Pro A1278 from other year could provide a similar compatible cable, but the cable length was different: ok for testing purposes, but not for a replacement.
According to other posts, ...
I have Time Capsule and Time Machine setup on my MacBook Pro.
The Time Capsule is always available at home. The Time Machine is only available sometimes.
macOS never complains about the Time Machine drive being unavailable, unless it's been like 7 days (which almost never happens).
is it possible to format this so I can use it for backup storage?
Definitely. You can use Disk Utility for that.
Is there any advantage to keeping this internal drive as is with the OS files that are not used on there?
An advantage is that you'll be able to boot the machine if the external drive ever fails.
would they be required for recovery in future?
You can try starting in Safe Mode. Restart your Mac and immediately after your Mac starts (some Mac computers play a startup sound), press and hold the Shift key. Release the Shift key when you see the progress indicator. See if this works. If so edit your question mentioning that it works in safe mode, and leave a comment here.
It is not possible and even if it were it would be a very bad idea.
RAID 1 is to protect from hardware failure, and as described in the Apple document Create a disk set using Disk Utility on Mac mentioned by @user3439894 in comments, requires multiple disks (not partitions).
Mirrored (RAID 1) set: Protect your data against hardware failure with a mirrored ...
I've found a way to use some command line tools to recursively check hashes of the individual files. Here's my commands:
hashdeep -rel -r . > hashdeep-outout.txt
Hashdeep (which you can install via homebrew) will create a CSV file listing each individual file with various hashes including MD5 and SHA256. -rel lists the files with the relative path to ...
Your situation doesn't entirely makes sense to me (but maybe I'm reading too much into it). You need zero space and zero functioning drive to boot to Internet recovery. Since you mentioned reformatting as a solution. I wanted to share the official steps for an erase install (for the curious)
Disk Utility's RAID support is patchy at best.
I recommend using SoftRaid. The 'Lite' version is sufficient for basic needs, and costs $50.
I use it on my G-RAID unit. I've replaced the drives once, and SoftRaid handled the re-population of each new drive in turn effortlessly.
I assume you're looking at the About This Mac Storage tab; dealing with that "Other" category is tough (illustrated by the wealth of search results for "mac storage other"), as it is comprised of a combination of files in many locations.
A recommendation would be to click the Manage button (Apple Menu -> About This Mac -> Storage) ...
It’s highly unlikely USB can slow down your mac since it has a minimum of 2x Thunderbolt 3 ports and likely 4 of them. The bandwidth there is way more than USB could saturate. It’s much more likely you need to look at the OS and apps running and rule out interference or USB cable / hub issues with some troubleshooting to note exactly what’s connected and do ...
I fixed this by doing the following:
I ran diskutil list. Then from that list, I checked which part of my disk was the one apple was using in the GUI in my original question by checking which one's size was also 42.74 GB (Its identifier was disk0s2 in my case).
I ran sudo diskutil apfs resizeContainer [the identifier we retrieved above] [the size we want ...