Reed–Solomon error correction
In order to increase redundancy, data uploaded onto Backblaze's data center is sharded into 17 data pieces and three parity shards for each file. Parity shard bits are computed by the Reed–Solomon error correction algorithm. The shards are stored in 20 different drives, each in a separate cabinet to increase resilience to a power loss to an entire cabinet, or other physically-based issue. Backblaze states that its 'Vault' architecture is designed with 99.999999999% annual durability.