External devices are ideal for simply creating a backup rather quickly...but using it as a boot device? Only for (re-)installing the operating system, nothing more.
-Shades
Thank you, Shades and Tomos. Yes, the above quote is exactly what I am aiming for.
I read that SSD HDs give no warning when they brick, and as mentioned, my laptop SSD is already quite old. I appreciate your water hose analogy, and offer another; a spare tire. If my SSD dies, I was hoping to be able to just boot from the external SATA USB, go online to get me a replacement SSD, re-copy the SATA USB clone onto the new internal SSD, and continue to reserve the external SATA as a backup spare copy of the OS.
The BIOS does offer the Boot options to boot from external USB hard drive, thumb drive, or disk. But so far, although I copied the OS to the external SATA USB HD, it just won't boot from it. So if my internal SSD ever dies, how am I supposed to save my OS which is loaded with the accumulated sum total of untold hours and days of hard work?
I did see where Seagate offers a sort of 'kit' consisting of a new SSD plus the necessary peripherals to clone your OS from your old internal SSD somehow, but forget the details, and don't have the money to get it (for now anyways). I also got burned by Seagate a while back with a whiny new HD which I returned to them, and they returned to me, and which eventually died prematurely just outside of warranty after a whiny abbreviated lifespan; so I'm not prejudiced, but they did burn me once.