nvme-compare-and-write · shipping · also NVMe fused Compare and Write

NVMe Compare and Write

NVMe Compare and Write is an optional fused operation that conditionally replaces an LBA range when its stored contents match supplied comparison data.

SPDK submits the pair with first/second fusion flags, adjacent on one queue and using the same range; submission is not completion. [2] Compare success alone cannot establish Write success; inspect both completion records and the applicable size and boundary limits. [1] A constructed slot-claim model enumerates the race in separate compare/write steps; it is not a hardware measurement. [3]

Relations

related

Compare-and-swap, NVMe reservation, Conditional write, Linearizability

Limitations

• The operation does not by itself fence delayed writes to other addresses or provide an application-wide transaction. [3]

Citations

1. NVM Express 1.3d (2019), sections 4.10 and 6.2.1; Identify Controller ACWU. Copyright 2007-2019 NVM Express, Inc. (accessed 2026-10-21)
2. SPDK NVMe Driver: asynchronous I/O, fused operations and queue-pair ownership (accessed 2026-10-21)
3. Hesela: NVMe conditional updates and complete constructed schedules (accessed 2026-10-21)

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