Hitachi HTS725050A9A364 Datasheet download pdf (Page 22)

7K500 OEM SPECIFICATION

Page 22 of 176

5 5

5 Data integrity

Data integrityData integrity

Data integrity

5.1

5.15.1

5.1 Data loss on power off

Data loss on power offData loss on power off

Data loss on power off

 Data loss will not be caused by a power off during any operation except the write operation.

 A power off during a write operation causes the loss of any received or resident data that has not

been written onto the disk media.

 A power off during a write operation might make a maximum of one sector of data unreadable. This

state can be recovered by a rewrite operation.

5.2

5.25.2

5.2 Write Cache

Write CacheWrite Cache

Write Cache

When the write cache is enabled, the write command may complete before the actual disk write operation

finishes. This means that a power off, even after the write command completion, could cause the loss of

data that the drive has received but not yet written onto the disk.

In order to prevent this data loss, confirm the completion of the actual write operation prior to the power

off by issuing a

 Soft reset

 COMRESET

 Flush Cache command

 Standby command

 Standby Immediate command

 Sleep command

Confirm the command’s completion.

5.3

5.35.3

5.3 Equipment status

Equipment statusEquipment status

Equipment status

The equipment status is available to the host system any time the drive is not ready to read, write, or seek.

This status normally exists at the power-on time and will be maintained until the following conditions are

satisfied:

 The access recalibration/tuning is complete.

 The spindle speed meets the requirements for reliable operation.

 The self-check of the drive is complete.

The appropriate error status is made available to the host system if any of the following conditions occur

after the drive has become ready:

 The spindle speed lies outside the requirements for reliable operation.

 The occurrence of a Write Fault condition.

5.4

5.45.4

5.4 WRITE safety

WRITE safetyWRITE safety

WRITE safety

The drive ensures that the data is written into the disk media properly. The following conditions are

monitored during a write operation. When one of these conditions exceeds the criteria, the write operation

is terminated and the automatic retry sequence is invoked.

 Head off track

 External shock

 Low supply voltage

 Spindle speed out of tolerance

 Head open/short

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Hitachi HTS725050A9A364 Datasheet Page 22

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