A lot depends what type of scanner your friend has as to whether or not it can pull MB codes. Usually either a glow plug module or individual glow plug is at fault. Cheaper to get it on a decent scanner first otherwise you could end up playing parts darts
Did the same and had it for around 45K miles and 9 years - no issues. Agree about the actuator as well, they do seem to go off eventually - mine was at 130K miles. Now done 170Kmiles and just passed MOT with perfect emissions output.
Does this help?
https://uk.pcmag.com/mobile-phone-accessories/141911/the-best-wireless-adapters-for-carplay-and-android-auto-in-2022
Those you have chosen are more expensive than the main field
RAID is a useful tool if you need high availability such as production environments, overkill for a personal/domestic backup. The OP is just using the drive for backups so having a simpler solution with more than one copy of the backup is the way to go, less hassle, lower cost, high reliability.
RAID can fail and when it does you can loose everything - I know I have seen it happen in my career in IT more than once. Add to that most home NAS units will not have UPS protection in the event of a power failure - a well known way of taking down a RAID array.
A better and cheaper option for...