Sony SDX-800V/R manual Disconnect-Reconnect Page 02h, Dtdc

MODE SELECT 6.Command Specification

6.7.1. Disconnect-Reconnect Page (02h)

The drive supports the Disconnect-Reconnect Page which has the following format:

Table 6-40: Disconnect-Reconnect Page

Bit	7	6	5		4		3		2	1		0
Byte
0	PS(0)	Reserved					Page Code (02h)
1					Page Length (0Eh)
2					Buffer Full Ratio (00h)
3					Buffer Empty Ratio (00h)
4	(MSB)				Bus Inactivity Limit (00h)
5												(LSB)
6	(MSB)			Disconnect Time Limit (0000h)
7												(LSB)
8	(MSB)				Connect Time Limit (00h)
9												(LSB)
10	(MSB)			Maximum Burst Size (4000h)
11												(LSB)
12	Reserved		Fair Arbitration (00b)					Reserved			DTDC
13						Reserved
14						Reserved
15						Reserved

Buffer Full Ratio, Buffer Empty Ratio, Bus Inactivity Limit and Connect Time Limit fields are not supported by the drive if set to non-ZERO values a CHECK CONDITION status is returned with ILLEGAL REQUEST sense key set.

Disconnect Time Limit: This field indicates the minimum time in 100 microsecond increments that the drive shall wait after releasing the SCSI bus before attempting re-selection. This should be 0 and this is non-changeable field.

Maximum Burst Size: This field defines the maximum amount of data that the drive shall transfer during a data phase before disconnecting. This value is expressed in increments of 512 bytes. This is non-changeable field and should be 4000h.

Note: 512 (200h) ⋅ 16384 (4000h) = 8388608(8 Mbytes) which means that the Maximum Burst Size is approximately equal to SDX-800V Buffer size for SCSI side.

FAIR ARBITRATION: This field indicates whether the drive shall use fair or unfair arbitration when requesting an interconnect tenancy. Setting this field to 1 will enable the SCSI Bus Fairness protocol. Setting this field to zero will disable it. The drive determines fairness by monitoring prior arbitration attempts by other SCSI devices. It shall postpone arbitration for itself until all lower priority SCSI devices that previously lost arbitration either win a subsequent arbitration or discontinue their arbitration attempts. It shall monitor the arbitration attempts of the other SCSI devices and refresh the fairness register with the SCSI ID’s of any lower priority SCSI devices that lost arbitration. This field is not support.

DTDC: This field defines further restrictions on when a disconnect is permitted.

DTDC	Description
00b	Data transfer disconnect control is not used. Disconnect is controlled by the other field in this
	page.
01b	A target shall not attempt to disconnect once the data transfer of a command has started until all
	data the command is to transfer has been transferred. The connect time limit and bus inactivity
	limit are ignored during the data transfer.
10b	Reserved
11b	A target shall not attempt to disconnect once the data transfer of a command has started until the
	command is complete. The connect time limit and bus inactivity limit are ignored once data
	transfer has started.

SONY AIT-3Ex drive SDX-800V series Ver.1.1 6-41