Erasure Coding – This is data coding added to a data set to enable a storage system to recover from the loss (erasure) of parts of the data set caused by, for example, a storage drive failure. A piece of data is split into sectors or chunks. These have codes generated from them and added to them with the now redundant data sectors stored across different drives. Should a drive fail the remaining data sectors, with the added erasure coded data, can be used to recover the lost (erased) data.
Erasure coding requires less overhead (added redundant data codes) in general than a RAID data protection scheme. Erasure Coding schemes can be described as 4+2P (4 data and 2 parity), 4+3P, 8+2P, and 8+3P, etc.