Seagate MEDALIST 1080SL Product Manual page 46

36 Medalist 1080sl SCSI Product Manual, August 1995
Bytes 2–3 The defect list length is the length, in bytes, of the defect list
that follows the header. For each sector to be reallocated,
the defect list contains one defect descriptor that contains
8 bytes in either the bytes-from-index format or the physical
sector format. A length of zero indicates no DList follows;
this is not an error.
Bytes 4– n The two types of defect descriptors are described in Sec-
tions 3.4.4.4 and 3.4.4.5. A length of zero indicates no
DList follows; this is not an error.
3.4.4.4 Defect descriptor—bytes-from-index format
Defects are specified in the bytes-from-index format when the defect list
format field is 100 . See byte 1 of the Format Unit command in
Binary
Section 3.4.4.
Each defect descriptor in the bytes-from-index format specifies the
beginning of a single-byte defect location on the disc. Each defect
descriptor is composed of the cylinder number of the defect, the head
number of the defect and the number of bytes-from-index to the defect
location. The defect descriptors are always listed in ascending order.
A value for defect bytes-from-index of FFFFFFFF
sign the entire track) is illegal.
The information in the following table is for each defect.
Bytes
7 6
0–2
3
4–7
3.4.4.5 Defect descriptor—physical sector format
Defects are specified in the physical sector format when the defect list
format field is 101 . See byte 1 of the Format Unit command in
Binary
Section 3.4.4.
Each defect descriptor for the physical sector format specifies a sector-
size defect location is composed of the cylinder number of the defect,
the head number of the defect and the defect sector number. The defect
descriptors must be in ascending order.
(which means reas-
H
Bits
5 4 3 2
Cylinder number of defect
Head number of defect
Defect bytes-from-index
1 0