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Fujitsu MHN2150AT Manual/User Guide - Page 213

Read-Ahead Cache

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6.4 Read-Ahead Cache Index Sector (Physical) 0 1 2 3 4 5 6 Cylinder 0 Defective sector Head 0 0 1 2 3 (unu4sed) 5 6 Sector (Logical) Alternate cylinder Head 0 Already assigned Defective sector is assigned to unassigned sector. 658 659 658 659 Notes: 1) 4 alternate cylinders are provided for each head in zone 14 (inner side). 2) When an access request to logical sector 4 is specified, the device accesses the alternated sector in the alternate cylinder instead of sector 4. When an access request to sectors next to logical sector 5 is specified, the device seeks to cylinder 0, head 0, and continues the processing. Figure 6.6 Alternate cylinder assignment (3) Automatic alternate assignment The device performs the automatic alternate assignment when ECC correction performance is increased during read error retry, a read error is recovered. Before automatic alternate assignment, the device performs rewriting the corrected data to the erred sector and rereading. If no error occurs at rereading, the automatic alternate assignment is not performed. An unrecoverable write error occurs during write error retry, automatic alternate assignment is performed. 6.4 Read-Ahead Cache After read command which involves read data from the disk medium is completed, the read-ahead cache function reads the subsequent data blocks automatically and stores the data to the data buffer. C141-E120-02EN 6-11

Section	Page
Front Cover	1
FOR SAFE OPERATION	2
Revision History	3
Preface	5
Important Alert Items	9
Manual Organization	11
Contents	13
Figures	18
Tables	19
CHAPTER 1 Device Overview	21
1.1 Features	22
1.1.1 Functions and performance	22
1.1.2 Adaptability	22
1.1.3 Interface	23
1.2 Device Specifications	24
1.2.1 Specifications summary	24
1.2.2 Model and product number	25
1.3 Power Requirements	25
1.4 Environmental Specifications	27
1.5 Acoustic Noise	28
1.6 Shock and Vibration	28
1.7 Reliability	29
1.8 Error Rate	30
1.9 Media Defects	30
1.10Load/Unload Function	30
CHAPTER 2 Device Configuration	33
2.1 Device Configuration	34
2.2 System Configuration	36
2.2.1 ATA interface	36
2.2.2 1 drive connection	36
2.2.3 2 drives connection	36
CHAPTER 3 Installation Conditions	39
3.1 Dimensions	40
3.2 Mounting	41
3.3 Cable Connections	47
3.3.1 Device connector	47
3.3.2 Cable connector specifications	48
3.3.3 Device connection	48
3.3.4 Power supply connector (CN1)	49
3.4 Jumper Settings	49
3.4.1 Location of setting jumpers	49
3.4.2 Factory default setting	50
3.4.3 Master drive-slave drive setting	50
3.4.4 CSEL setting	51
CHAPTER 4 Theory of Device Operation	53
4.1 Outline	54
4.2 Subassemblies	54
4.2.1 Disk	54
4.2.2 Head	54
4.2.3 Spindle	55
4.2.4 Actuator	55
4.2.5 Air filter	55
4.3 Circuit Configuration	56
4.4 Power-on Sequence	59
4.5 Self-calibration	60
4.5.1 Self-calibration contents	60
4.5.2 Execution timing of self-calibration	61
4.5.3 Command processing during self-calibration	62
4.6 Read/write Circuit	62
4.6.1 Read/write preamplifier (HDIC)	62
4.6.2 Write circuit	62
4.6.3 Read circuit	65
4.6.4 Digital PLL circuit	66
4.7 Servo Control	67
4.7.1 Servo control circuit	67
4.7.2 Data-surface servo format	70
4.7.3 Servo frame format	72
4.7.4 Actuator motor control	73
4.7.5 Spindle motor control	74
CHAPTER 5 Interface	77
5.1 Physical Interface	78
5.1.1 Interface signals	78
5.1.2 Signal assignment on the connector	79
5.2 Logical Interface	82
5.2.1 I/O registers	83
5.2.2 Command block registers	84
5.2.3 Control block registers	89
5.3 Host Commands	89
5.3.1 Command code and parameters	90
5.3.2 Command descriptions	92
5.3.3 Error posting	164
5.4 Command Protocol	166
5.4.1 PIO Data transferring commands from device to host	166
5.4.2 PIO Data transferring commands from host to device	168
5.4.3 Commands without data transfer	170
5.4.4 Other commands	172
5.4.5 DMA data transfer commands	172
5.5 Ultra DMA Feature Set	175
5.5.1 Overview	175
5.5.2 Phases of operation	176
5.5.3 Ultra DMA data in commands	176
5.5.4 Ultra DMA data out commands	181
5.5.5 Ultra DMA CRC rules	185
5.5.6 Series termination required for Ultra DMA	186
5.6 Timing	187
5.6.1 PIO data transfer	187
5.6.2 Multiword data transfer	188
5.6.3 Ultra DMA data transfer	189
5.6.4 Power-on and reset	202
CHAPTER 6 Operations	203
6.1 Device Response to the Reset	204
6.1.1 Response to power-on	204
6.1.2 Response to hardware reset	205
6.1.3 Response to software reset	207
6.1.4 Response to diagnostic command	208
6.2 Power Save	209
6.2.1 Power save mode	209
6.2.2 Power commands	210
6.3 Defect Management	211
6.3.1 Spare area	211
6.3.2 Alternating defective sectors	211
6.4 Read-Ahead Cache	213
6.4.1 Data buffer configuration	214
6.4.2 Caching operation	214
6.4.3 Usage of read segment	216
6.5 Write Cache	222
Glossary	225
Acronyms and Abbreviations	229
Comment Form	231
Spine	233