Home > Storage > PowerMax and VMAX > Data Protection > Dell PowerMax: Reliability, Availability, and Serviceability > T10 Data Integrity Field
PowerMaxOS supports industry standard T10 Data Integrity Field (DIF) block cyclic redundancy code (CRC) for track formats. For open systems, this enables a host-generated DIF CRC to be stored with user data and used for end-to-end data integrity validation. Additional protections for address and control fault modes provide increased levels of protection against faults. These protections are defined in user-definable blocks supported by the T10 standard. Address and write status information is stored in the extra bytes in the application tag and reference tag portion of the block CRC.
PowerMaxOS further increases data integrity with T10-DIF+ which has additional bits for detecting stale data address faults, control faults and sector signature faults that are not detected in a standard T10-DIF. T10-DIF+ is performed every time data is moved; across the internal fabric, to or from drives, and on the way back to the host on reads.
On the backend, the T10-DIF codes for the expected data is stored and the checksums are verified when the data is read from the host. In addition, a one-byte checksum for each 8 K of data is kept in the track table (not stored with the data) that is used for independent validation of the data against the last version written to the array. This provides protection against situations such as: