It was a Sun enclosure, so proprietary and no documentation on the raw disk layout.
I'm not sure what you mean regarding how I wrote it, it's a single C file I wrote on my workstation that I had attached the enclosure to in JBOD mode so I could read every disk directly.
[0] https://dev.to/rkeene/raid5-lost-raid5-recovered-3kld
[1] https://www.rkeene.org/projects/info/resources/diatribes/blo...