Figure 2-3 Sector Reallocation - Hitachi DK32EJ - Ultrastar Series 36.9 GB Hard Drive Reference Manual

The replacement sector is assigned to the next defective sector, to reduce
rotational latency.
The controller executes a verification after formatting if C scheme is specified. If
an error is found, the controller identifies the error sector as defective and
reformats the track and the cylinder.
The controller adds defects identified by D and C schemes to the current G list
and saves the new G list in the system area.
(8) Block Reassignment
Unrecoverable error blocks caused by growing defects may be reassigned by the
REASSIGN BLOCKS command.
By REASSIGN BLOCKS command, the controller identifies one or more sectors
of the specified logical block as defective, and reassigns them as alternate spare
sectors.
The error block address ( logical block address ) is informed to the host computer
by information bytes of sense data.
An example of reallocating an alternate spare sector is shown in Figure 2-3.
Before
0
After
0
(9) Suggestion for Format Processing
· It is required to reformat medium by the FORMAT UNIT command if the
block length and/or the number of alternate spare area was changed by the
MODE SELECT command.
A command to access the medium is reported the CHECK CONDITION
status with the NOT READY sense key and Medium Format Corrupted
sense code if the FORMAT UNIT command is not executed after the change
with the related Mode parameter.
· This sense key is also reported when the Format command is terminated
during a format.
2 PRODUCT SPECIFICATION OUTLINE
Error sector
1 2
Defective sector (Bad Sector)
2
Reallocated (with sector skipping)

Figure 2-3 Sector Reallocation

Sector number
3
3
OEM MANUAL:K6602771
Alternate
N
Spare Sector
(Reserved
Sector)
N 1
Revision: 2 / Date: 2002.12.19
Page: 25 / 313