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OptiNAND

OptiNAND is a flash-assisted HDD architecture that integrates an embedded iNAND device with disk-controller hardware and firmware.

Related Observatory article: OptiNAND on hesela.com

Flash holds drive metadata, including sector-level write accounting for targeted ATI refresh; it does not by itself determine whether recording uses CMR or SMR. [1]

This is not synonymous with a hybrid drive's user-data read cache. ArmorCache is a distinct supported-model feature for retaining buffered writes on emergency power loss, so OptiNAND flash can also contain user data. [2]

Relations

related
hdd, ati-refresh, armorcache, sshd

Citations

  1. Western Digital. Reimagining HDDs with OptiNAND Technology, August 2022, printed pp. 1-4. (accessed 2026-10-16)
  2. Western Digital. ArmorCache Write Cache Data Protection, mechanism and WCE/WCD scope, printed pp. 1-2. (accessed 2026-10-16)

Further reading

  1. Hesela. OptiNAND metadata is not the ArmorCache guarantee: model and system boundaries. (accessed 2026-10-16)
Sources & caveats

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