Mode Page 2 (Disconnect/Reconnect Parameters) - IBM Ultrastar 36LZX Specifications

8.8.4Mode Page 2 (Disconnect/Reconnect Parameters)

Byte
7 6
0 PS RSVD=0
1
2
3
(MSB)
4-5
(MSB)
6-7
(MSB)
8-9
(MSB)
10-11
12 Fair arbitration
13-15
Figure 84. Mode Page 2 (Disconnect/Reconnect Parameters )
The disconnect/reconnect page provides the initiator with the means to tune the performance of the
SCSI bus.
An initiator may use the IDENTIFY message to grant the drive the general privilege of disconnecting.
(Disconnect requests may still be selectively rejected by the initiator by issuing a MESSAGE REJECT).
The drive uses the disconnect/reconnect parameters to control reconnection during READ (operation
code 08h and 28h) and WRITE ( 0Ah, 2Ah and 2E).
Ÿ Read Buffer Full Ratio is the numerator of a fraction whose denominator is 256. The fraction indi-
cates how full the drive data buffer should be before attempting to reconnect to the SCSI bus. If the
ratio is set to 0h, the target will calculate and use an optimal ratio based on the negotiated transfer
rate.
Ÿ Write Buffer Empty Ratio is the numerator of a fraction whose denominator is 256. The fraction
indicates how empty the drive data buffer should be before attempting to reconnect to the SCSI bus.
If the ratio is set to 0h, the target will calculate and use an optimal ratio based on the negotiated
transfer rate.
Ÿ Maximum Burst Size is the maximum amount of data that the Target transfers during a data phase
before disconnecting if the Initiator has granted the disconnect privilege. This value is expressed in
increments of single block size (for example, a value of 0001h means 512 bytes, 0002h means 1024
bytes when the block size is 512 bytes). Disconnections attempted by the Target are on block bound-
aries only. For the case when (Maximum Burst Size x Block Size) is less than the Block Length, the
Bit
5 4
Page Code = 02h
Page Length = 0Eh
Read Buffer Full Ratio
Write Buffer Empty Ratio
Bus Inactivity Limit = 0
Disconnect Time Limit = 0
Connect Time Limit = 0
Maximum Burst Size
DIMM
Reserved = 0
Ultrastar 36LZX hard disk drive specifications
3 2 1
RSVD DTDC
105
Default
0
82h
0Eh
00h
00h
00h
(LSB) 00h
00h
(LSB) 00h
00h
(LSB) 00h
00h
(LSB) 00h
00h
00h
00h
00h