User Manual

SCSI Commands Reference Manual, Rev. J 82

www.seagate.com Direct Access Block commands (SPC-5 and SBC-4)

3.3.5.3 Extended bytes from index address descriptor

A format type of 001b specifies the extended bytes from index address descriptor defined in table 46. For the FORMAT UNIT

command and the READ DEFECT DATA command, this descriptor specifies the location of a defect that is either:

a) the length of one track;

b) is less than the length of a physical block; or

c) a defect that starts from one address descriptor and extends to the next address descriptor.

For the Translate Address diagnostic pages, this descriptor specifies the location of an LBA. If format type 001b is used in the

SUPPLIED FORMAT field of a Translate Address Output diagnostic page (see 5.1.4), and the MADS bit in the ADDRESS TO

TRANSLATE field is set to one, then the device server shall terminate the SEND DIAGNOSTIC command with CHECK CONDITION

status with the sense key set to ILLEGAL REQUEST and the additional sense code set to INVALID FIELD IN PARAMETER LIST.

CYLINDER NUMBER field

The CYLINDER NUMBER field contains the cylinder number.

HEAD NUMBER field

The HEAD NUMBER field contains the head number.

MADS bit

A multi-address descriptor start (MADS) bit set to one specifies that this descriptor defines the beginning of a defect that spans multiple

address descriptors. The defect may be a number of sequential physical blocks on the same cylinder and head (i.e., a track) or may be a number

of sequential tracks on the same head. A MADS bit set to zero specifies that:

a) this descriptor defines the end of a defect if the previous address descriptor has the MADS bit set to one; or

b) this descriptor defines a single defective physical track (i.e., the BYTES FROM INDEX field contains FFF_FFFFh) or a single defective physical

block (i.e., the BYTES FROM INDEX field does not contain FFF_FFFFh).

See SBC-4 for valid combinations of two address descriptors that describe a defect.

BYTES FROM INDEX field

a) if not set to FFF_FFFFh, contains the number of bytes from the index (e.g., from the start of the track) to the location being described; or

b) if set to FFF_FFFFh, specifies that the entire track is being described.

For sorting bytes from index format address descriptors, the cylinder number is the most significant part of the address and the bytes from

index is the least significant part of the address. More than one logical block may be described by this descriptor.

Table 46 Bytes from index format address descriptor (100b)

Bit

Byte

7 6 5 4 3 2 1 0

(MSB)

CYLINDER NUMBER

. . .

(LSB)

HEAD NUMBER

MADS Reserved (MSB)

. . .

BYTES FROM INDEX

(LSB)