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Fujitsu MHT2030AT Manual/User Guide - Page 239

Write Cache, 6.5.1 Cache operation

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6.5 Write Cache 6.5 Write Cache Write Cache is the function for reducing the command processing time by separating command control to disk media from write control to disk media. When Write Cache is permitted, the write command can be keep receiving as long as the space available for data transfers remains free on the data buffer. Because of this function, command processing appears to be completed swiftly from the viewpoint of the host. It improves system throughput. 6.5.1 Cache operation (1) Command that are targets of caching The Commands that are targets of caching are as follows: • WRITE SECTOR (S) • WRITE MULTIPLE • WRITE DMA • WRITE SECTOR (S) EXT • WRITE MULTIPLE EXT • WRITE DMA EXT However, the caching operation is not performed when the caching function is prohibited by the SET FEATURES command. (2) Invalidation of cached data If an error occurs during writing onto media, write processing is repeated up to as many times as specified for retry processing. If retry fails for a sector because the retry limit is reached, automatic alternate sector processing is executed for the sector. If the automatic alternate sector processing fails, the data in the sector for which automatic alternate sector processing failed is invalidated without being guaranteed. If data remains in sectors following a sector for which automatic alternate sector processing failed, the data is invalidated without being guaranteed. Moreover, when the command (clause 6.4.2(3)) is accepted and HOST CRC Error is generated, the cashing data is invalidated. • If a Reset or command is received while a transfer of one sector of data is in progress, data is not written in the sector of the media where the interruption occurred, and sectors accepted before interruption occurred is written in the medium. C141-E192-02EN 6-19

Section	Page
Front Cover	1
FOR SAFE OPERATION	2
Revision History	3
Preface	5
Important Alert Items	9
Manual Organization	11
Contents	13
Illustrations	18
Figures	18
Tables	20
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	26
1.4 Environmental Specifications	28
1.5 Acoustic Noise	29
1.6 Shock and Vibration	29
1.7 Reliability	30
1.8 Error Rate	31
1.9 Media Defects	31
1.10 Load/Unload Function	31
1.11 Advanced Power Management	32
CHAPTER 2 Device Configuration	35
2.1 Device Configuration	36
2.2 System Configuration	37
2.2.1 ATA interface	37
2.2.2 1 drive connection	37
2.2.3 2 drives connection	38
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
3.4.5 Power Up in Standby setting	52
CHAPTER 4 Theory of Device Operation	53
4.1 Outline	54
4.2 Subassemblies	54
4.2.1 Disk	54
4.2.2 Spindle	54
4.2.3 Actuator	54
4.2.4 Air filter	55
4.3 Circuit Configuration	55
4.4 Power-on Sequence	58
4.5 Self-calibration	59
4.5.1 Self-calibration contents	59
4.5.2 Execution timing of self-calibration	60
4.5.3 Command processing during self-calibration	61
4.6 Read/write Circuit	61
4.6.1 Read/write preamplifier (PreAMP)	61
4.6.2 Write circuit	61
4.6.3 Read circuit	63
4.6.4 Digital PLL circuit	64
4.7 Servo Control	65
4.7.1 Servo control circuit	65
4.7.2 Data-surface servo format	68
4.7.3 Servo frame format	70
4.7.4 Actuator motor control	71
4.7.5 Spindle motor control	72
CHAPTER 5 Interface	75
5.1 Physical Interface	76
5.1.1 Interface signals	76
5.1.2 Signal assignment on the connector	77
5.2 Logical Interface	80
5.2.1 I/O registers	81
5.2.2 Command block registers	82
5.2.3 Control block registers	87
5.3 Host Commands	88
5.3.1 Command code and parameters	88
5.3.2 Command descriptions	92
5.3.3 Error posting	182
5.4 Command Protocol	184
5.4.1 PIO Data transferring commands from device to host	184
5.4.2 PIO Data transferring commands from host to device	187
5.4.3 Commands without data transfer	188
5.4.4 Other commands	190
5.4.5 DMA data transfer commands	190
5.5 Ultra DMA Feature Set	192
5.5.1 Overview	192
5.5.2 Phases of operation	193
5.5.3 Ultra DMA data in commands	193
5.5.4 Ultra DMA data out commands	198
5.5.5 Ultra DMA CRC rules	202
5.5.6 Series termination required for Ultra DMA	203
5.6 Timing	204
5.6.1 PIO data transfer	204
5.6.2 Multiword data transfer	205
5.6.3 Ultra DMA data transfer	206
5.6.4 Power-on and reset	219
CHAPTER 6 Operations	221
6.1 Device Response to the Reset	222
6.1.1 Response to power-on	222
6.1.2 Response to hardware reset	223
6.1.3 Response to software reset	225
6.1.4 Response to diagnostic command	226
6.2 Power Save	227
6.2.1 Power save mode	227
6.2.2 Power commands	229
6.3 Defect Processing	229
6.3.1 Spare area	229
6.3.2 Alternating processing for defective sectors	230
6.4 Read-ahead Cache	232
6.4.1 DATA buffer structure	232
6.4.2 Caching operation	233
6.4.3 Using the read segment buffer	235
6.5 Write Cache	239
6.5.1 Cache operation	239
Glossary	243
Acronyms and Abbreviations	247
Index	249
Comment Form	251