6.4.1Spare area

Following two types of spare area are provided in the user space.

1)Spare sector for sector slip:

used for alternating defective sectors at formatting in shipment (128 sectors/32 cylinders)

2)Spare cylinder for alternative assignment:

used by automatic alternative assignment. (4 cylinder/drive)

6.4.2Alternating defective sectors

The two alternating methods described below are available:

(1)Sector slip processing

A defective sector is not used and is skipped and a logical sector address is assigned to the subsequent normal sector (physically adjacent sector to the defective sector).

When defective sector is present, the sector slip processing is performed in the formatting. Figure 6.7 shows an example where (physical) sector 5 is defective on head 0 in cylinder 0.

Index

Cylinder 0

Head 0

 

 

Sector (physical)

 

 

 

 

 

 

 

 

1

2

3

4

5

6

7

8

796

797

798

 

 

 

 

 

Defective

 

 

 

 

 

 

 

 

 

 

 

 

sector

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1

2

3

4

 

5

6

7

795

796

797

unused

If an access request to sector 5 is specified, the device accesses physical sector 6 instead of sector 5.

Figure 6.7 Sector slip processing

C141-E110-02EN

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Image 188
Fujitsu MPG3XXXAT manual Spare area, Alternating defective sectors