IBM DTCA-24090 Hard Drive Specifications - Page 23

Data Integrity

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4.0 Data Integrity 4.1 Data Loss by Power Off The drive retains recorded data under all non-write operations. No more than one sector can be lost by power down during write operation while write cache is disabled. Power off during write operation may make an incomplete sector which will report hard data error when read. The sector can be recovered by a re-write operation. Hard reset does not cause any data loss. 4.2 Write Cache Power off while write cache is enabled may cause loss of data which are remaining in the cache and have not been flushed onto the disk media. This means that there is a possibility that power off even after write command completion may cause loss of data. There are ways to check if all data in the write cache have been flushed onto the disk. Checking just before power off is recommended to prevent data loss. − To confirm successful completion of Software Reset. − To confirm successful completion of Flush Cache command. | − To confirm successful completion of Check Power Mode command. − To confirm successful completion of Standby command. − To confirm successful completion of Standby Immediate command. − To confirm successful completion of Sleep command. | Note: For Power Off Sequence, refer to 5.3.6, " Load/Unload" on page 24. 4.3 Equipment Status 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 power-on time and will be maintained until the following conditions are satisfied: Access recalibration/tuning is complete. Spindle speed meets requirements for reliable operation. Self-check of drive is complete. Appropriate error status is made available to the host system if any of the following conditions occur after the drive has once become ready: Spindle speed outside requirements for reliable operation. Occurrence of a WRITE FAULT condition. © Copyright IBM Corp. 1997 15

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4.0
Data Integrity
4.1
Data Loss by Power Off
The drive retains recorded data under all non-write operations.
No more than one sector can be lost by power down during write operation while write cache is disa-
bled.
Power off during write operation may make an incomplete sector which will report hard data error when
read. The sector can be recovered by a re-write operation.
Hard reset does not cause any data loss.
4.2
Write Cache
Power off while write cache is enabled may cause loss of data which are remaining in the cache and have
not been flushed onto the disk media.
This means that there is a possibility that power off even after write command completion may cause
loss of data.
There are ways to check if all data in the write cache have been flushed onto the disk. Checking just
before power off is recommended to prevent data loss.
-
To confirm successful completion of Software Reset.
-
To confirm successful completion of Flush Cache command.
|
-
To confirm successful completion of Check Power Mode command.
-
To confirm successful completion of Standby command.
-
To confirm successful completion of Standby Immediate command.
-
To confirm successful completion of Sleep command.
|
Note:
For
Power Off Sequence
, refer to 5.3.6, “ Load/Unload” on page 24.
4.3
Equipment Status
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 power-on time and will be maintained until the following conditions are satisfied:
Access recalibration/tuning is complete.
Spindle speed meets requirements for reliable operation.
Self-check of drive is complete.
Appropriate error status is made available to the host system if any of the following conditions occur after
the drive has once become ready:
Spindle speed outside requirements for reliable operation.
Occurrence of a WRITE FAULT condition.
Copyright IBM Corp. 1997
15