scsi-field-pointer · shipping · also SCSI sense field pointer

SCSI field pointer

A SCSI field pointer identifies a byte in the command or parameter data associated with an ILLEGAL REQUEST condition.

For ILLEGAL REQUEST, C/D=1 selects the command descriptor block and C/D=0 selects data parameters. The two-byte pointer is zero-based. BPV=1 adds a bit position; BPV=0 leaves that bit position unavailable, not bit zero. [1]

Fixed-format sense places this data at bytes 15-17 and gates its interpretation with SKSV. Descriptor format uses type 02h, additional length 06h, with the three sense-key-specific bytes at descriptor offsets 4-6. Other sense keys give these bytes different meanings. [2]

A field pointer is separate from the Information field and is not a failing LBA. Keep the original command, received sense length and validity flags. A formatted decoder message is not proof of a conforming response: an offline malformed-descriptor example still prints a pointer in the tested decoder build. [3]

Relations

related: SCSI sense key, SCSI Information field, SCSI CHECK CONDITION

Limitations

The reported byte need not be the byte whose modification resolves the request.

Citations

Quantum Scalar i3: Request Sense response and sense-key-specific field definitions (accessed 2026-11-08)
Seagate SCSI Commands Reference Rev. M, Tables 14, 17-19 and sections 2.4.1.1.4-2.4.1.2 (accessed 2026-11-08)
Hesela: finding the rejected command field, with offline decoder observations (accessed 2026-11-08)

Sources & caveats

The native examples use invented byte buffers and sg3-utils 1.46-3ubuntu4.1, not commands sent to a drive. [3]
Rev. M section 2.4.1.1.4.1 prints 01h in one sentence, while its Tables 14 and 17 identify 02h; the pinned decoder also dispatches type 02h. [2]

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