An improved technique applies polar codes to storage data to improve the reliability of a storage system that uses high-performance, solid-state disks as part of a RAID group for storing frequently-accessed data. Along these lines, a high-performance storage system having n solid-state disks assigns k of those disks as payload disks. The storage system partitions the payload data into a data vector that has k data symbols. The storage system then applies, to the k payload symbols, a (n, k) polar code generator matrix derived from k rows of the ┌ log2 n┐-times Kronecker product of the matrix   ( 1 0 1 1 ) to produce n encoded symbols and stores each of the encoded payload symbols in a solid-state disk of the RAID group.