nvme-unexpected-power-losses · shipping · also Unexpected Power Losses, UPL, NVMe Unsafe Shutdowns, Unsafe Shutdowns, unsafe_shutdowns

NVMe Unexpected Power Losses

NVMe Unexpected Power Losses is the SMART / Health Information log counter of main-power losses that meet the specification's incomplete-shutdown conditions.

Related Observatory article: NVMe Unexpected Power Losses on hesela.com

Formerly named Unsafe Shutdowns, the field counts power loss before the controller reports ready to be powered off (CSTS.SHST = 10b), plus specified out-of-band Admin-command cases in which Ignore Shutdown permits media access during or after shutdown processing. NVMe Base 2.3 places it at bytes 144 through 159. Its definition is not limited to a missing CC.SHN notification; readiness and media shutdown state matter. [2]

Relations

related

nvme-smart-log, nvme-media-data-integrity-errors, nvme-error-information-log-entries

Limitations

• This is a power-loss event count, not a count of corrupted files: an increase does not by itself prove data loss or identify its cause, while unprotected systems may suffer corruption. [1, 2]

Citations

1. Changes in NVM Express Specifications (August 2024), section 1.2.23.1, p. 15: rename and revised counting conditions (accessed 2026-10-14)
2. NVM Express Base Specification 2.3, section 5.2.12.1.3, Figure 210, p. 216: Unexpected Power Losses (accessed 2026-10-14)

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