Techniques for fault tolerant data storage

Described are techniques for performing data recovery processing for two failed devices included in a set of devices. It is determined whether the two failed devices are each one of the data devices, a horizontal parity device, or a diagonal parity device. Each of the data devices is partitioned into N-1 data segments. The horizontal parity device includes N horizontal parity segments each including parity information for a horizontal grouping of N-1 of the data segments. The diagonal parity device includes N diagonal parity segments each including parity information for a diagonal grouping of N-1 of the data segments. Recovery processing is performed to recover two failed devices in accordance with the diagonal parity device, the horizontal parity device, and the data devices.