I tried to implement reading RAID 6 array with 2 missing drives but failed. I followed this article but unfortunately it does not work for HP Smart Array P420. You can see my messy code for that here. It works for Linux RAID though, so I guess Smart Array Controllers codes that a little bit differently. I have no mathematical knowledge to figure out how it's calculate so I am reaching out for help.
I created 2 RAID 6 Arrays - with 4 drives and 5 drives. In each folder there are binary files with one stripe of data. Data drives: dn.bin, parity drive: parity.bin and reed solomon drive rs.bin.
For example with 4 drives, first byte of rs.bin and parity.bin is calculated from the first byte of d1.bin and d2.bin, second from second and so on.
With 4 drives I added all combinations of two bytes, with 5 drives I counld't fit all combinations of three bytes on one stripe but I hope that's enough.
All I need is some function that would allow me to calculate:
- one byte of missing data drive from all remaining data drives and rs drive
- one byte of two missing data drives from all remaining data drives, parity drive and rs drive
I tried for few long hours to figure out how it's calculated but I am unable, I know only basic math so if someone could help me with that I would be veeeery thankful and of course I will make honorable mention of one that would help me in the project README 🙏