nvme-host-read-commands · shipping · also Host Read Commands, HRC

NVMe Host Read Commands

NVMe Host Read Commands is the SMART / Health Information log counter of completed commands in the I/O command set's designated host-read class.

Related Observatory article: NVMe Host Read Commands on hesela.com

Base 2.3 places this 128-bit command count at bytes 64-79 of log 02h; it is not a byte quantity. Completed does not by itself mean successful. [1]

NVM Command Set 1.2 includes Compare, Copy and Read, whereas Data Units Read includes Compare, Read and Verify. Check the implemented revision before using these lists. [2]

The pinned smartctl implementation names this field nvme_smart_health_information_log.host_reads and also exports host_reads.commands at the JSON root. The neighboring host_reads.units is a different quantity; retain the full path in a collector. [3]

The similarly named Endurance Group Host Read Command class also includes Verify in NVM Command Set 1.2 section 1.4.2.1. It is not interchangeable with the SMART class above; retain the log identifier and collection scope, not only a shortened field name. [2]

Relations

related

NVMe SMART log, NVMe Data Units Read, NVMe Controller Busy Time

Limitations

• A cumulative command count is neither application IOPS nor a latency distribution; do not apply the Data Units Read byte multiplier to it. [1, 3]

Citations

1. NVM Express Base Specification 2.3, Figure 210, p. 215: read-data and command counters (accessed 2026-10-26)
2. NVM Express NVM Command Set 1.2, sections 1.4.2.1, 1.4.2.7-1.4.2.8 and 3.3.5: distinct read-command classes (accessed 2026-10-26)
3. smartmontools pinned nvmeprint.cpp: distinct data_units_read and host_reads JSON fields (accessed 2026-10-26)

JSON: /data/terms/nvme-host-read-commands.json