That must be RAID4, then? More expensive at the start, but you only sacrifice 25% of disc space to redundancy.
It is. Been too long in the IT business to feel safe with much else. (Except maybe a mirrored pair, but I’m not running high performance databases on it)
RAID 5 is most probably the RAID level. that is what will create a 25% overhead on 4 drives. It will allow for 1 drive failure. If 2 drives fail at the same time, it cannot be repaired.
RAID 0 has no overhead, but it also does not offer any redundancy. It is used for enhancing performance by writing across 2 drives acting as one logical drive. RAID 1 is what a mirrored drive would be.
Although most of my (non-work) content is stored in the cloud I hadn't got around to putting my TOTP collection up there. So I bit the bullet and setup a 2TB cloud solution and after using Easus I was able to recover 100% of my TOTP collection and am now working through all of the other missing files to rebuild. Everything in the cloud now. The link above was great because it filled in a few gaps in my collection.
Glad you managed to recover everything. Optical discs are still good. These days I do one back up onto 25Gb BD-R discs (35p for a HTL disc), written and checked using the free ImgBurn software. I used DVD and CD before that, back to 1998, and in my experience disc failure is incredibly rare.