nvme-dlfeat · shipping · also Deallocate Logical Block Features

NVMe DLFEAT

NVMe DLFEAT is an Identify Namespace field describing deallocated read values, Write Zeroes deallocation support and protection-information behavior.

Read behavior occupies bits 2:0: 0 is unreported, 1 selects zero bytes and 2 selects FFh bytes. Bit 3 separately indicates support for Write Zeroes DEAC; bit 4 selects CRC-based Guard behavior. Testing the whole byte for nonzero confuses these fields. [1]

Relations

related
Deallocated read behavior, NVMe DULBE, Discard, Protection information (PI)

Limitations

  • A field declaration is not evidence that a particular LBA was deallocated or that its physical copies were erased. [2]

Citations

  1. libnvme v1.13: namespace feature and DLFEAT field definitions (accessed 2026-10-21)
  2. NVM Express 1.4a: Figure 247, Figure 282 and section 6.7.1.1 (accessed 2026-10-21)

Further reading

  1. Hesela: interpreting deallocation fields (accessed 2026-10-21)
Sources & caveats
  • Reference interpretation is scoped to NVMe 1.4a and cross-checked against libnvme v1.13; no hardware commands were run.

JSON: /data/terms/nvme-dlfeat.json

Published by Hesela team · Updated

Report a correction · Editorial standards · Reuse guidance

Cite this page
Hesela team. NVMe DLFEAT. Hesela. 2026-10-21. https://hesela.dev/terms/nvme-dlfeat/