Sony SDX-800V manual BUS Device Reset 0Ch, Identify 80h-FFh, Ignore Wide Residue 23h, Ignore Field

5.SCSI Interface

5.3.11.BUS DEVICE RESET (0Ch)

This message is sent from an initiator to direct a target to clear all current commands. Upon recognizing this message, the currently executing command will be aborted and the drive will proceed to the BUS FREE state. The drive will then execute a hard reset which will leave the drive in a state as if it had been power-cycled. All data in the buffer will be written to tape before the reset is performed.

A BUS DEVICE RESET message should be used to reset the drive, rather than a hard reset, as this will only reset the drive rather than all the devices on the bus.

Due to the catastrophic nature of this command, it should be used cautiously in a multiple initiator system.

5.3.12.IDENTIFY (80h-FFh)

These messages are sent by either the initiator or the target to establish the physical connection path between an initiator and target for a particular logical unit. This message byte can have the following bits set:

Bit 7	This bit is always set to one to distinguish these messages from other messages.
Bit 6	This bit is only set to one by the initiator. When set to one, it indicates that the initiator has the ability to
	disconnect and reconnect.
Bit 5	LUNTAR: This bit is always ZERO to indicate that the LUNTRN field below is valid.
Bits 4-3	Reserved.

Bits 2-0LUNTRN: These bits specify a logical unit number in a target, and must always be set to ZERO as the unit is a single target, single logical unit device on the SCSI bus. The Logical Unit Number for the drive is fixed and is set to ZERO. Any other value will cause the unit to enter the status phase reporting CHECK CONDITION with the sense key set to COMMAND ABORTED.

Therefore, only the values 80h and C0h are supported.

When sent from a target to an initiator during reconnection, an implied RESTORE POINTERS message will be performed by the initiator prior to completion of this message, since at no time will a RESTORE POINTERS be sent.

5.3.13.IGNORE WIDE RESIDUE (23h)

Table 5-5: Ignore Wide Residue Message

Byte	Value
0	23	Message Code
1	01	Ignore

The IGNORE WIDE RESIDUE message (see table 5-5) shall be sent from the SDX-800V to indicate that the number of valid bytes sent during the last REQ/ACK handshake and REQB/ACKB handshake of a DATA IN phase is less than the negotiated transfer width. The ignore field indicates the number of invalid data bytes transferred. This message shall be sent immediately following that DATA IN phase and prior to any other messages. The ignore field is defined in table 5-6. More than one IGNORE WIDE RESIDUE message may occur during an I/O process.

	Table 5-6: Ignore Field
Ignore		Invalid data bits
		16-bit transfers
00h		Reserved
01h		DB (15-8)
02-FFh		Reserved

Even though a byte is invalid its corresponding parity bit shall be valid for the value transferred.

SONY AIT-3Ex drive SDX-800V series Ver.1.1 5-11