User Manual

SCSI Commands Reference Manual, Rev. J 434

www.seagate.com Parameters for direct access devices

5.3.24 Logical Unit mode page (18h) for SAS

The SAS Protocol-Specific Logical Unit mode page (see SPL-2) contains parameters that affect SSP target port operation on

behalf of the logical unit.

The mode page policy (see 5.4.14) for the Protocol-Specific Logical Unit mode page short format subpage shall be either shared

or per target port. If a SAS target device has multiple SSP target ports, the mode page policy should be per target port.

Parameters in this page shall affect all phys in the SSP target port if the mode page policy is per target port, and shall affect all

SSP target ports in the SAS target device if the mode page policy is shared.

Table 407 defines the format of the page for SAS.

PS bit

The PARAMETERS SAVEABLE (PS) bit is defined in 5.3.5.

SPF bit

The SPF bit shall be set to zero for access to the short format mode page.

PAGE CODE field

The PAGE CODE field shall be set to 18h.

PAGE LENGTH field

The PAGE LENGTH field shall be set to 06h.

PROTOCOL IDENTIFIER field

The PROTOCOL IDENTIFIER field shall be set to 6h indicating this is a SAS specific mode page.

TRANSPORT LAYER RETRIES bit

1 A TRANSPORT LAYER RETRIES bit set to one specifies that the target port shall support transport layer retries for XFER_RDY and DATA

frames for the logical unit as described in SAS-3 Transport Layer.

0 A TRANSPORT LAYER RETRIES bit set to zero specifies that transport layer retries shall not be used.

Table 407 Protocol-Specific Logical Unit mode page for SAS

Bit

Byte

7 6 5 4 3 2 1 0

0 PS SPF (0b) PAGE CODE (18h)

1 PAGE LENGTH (06h)

2 Reserved

TRANSPORT

LAYER RETRIES

PROTOCOL IDENTIFIER (6h)

3 Reserved

Reserved. . .