Hitachi 7K400 Specifications - Page 111

Address Offset Feature

Page 111 highlights

10.16 Address Offset Feature Computer systems perform initial code loading (booting) by reading from a predefined address on a disk drive. To allow an alternate bootable operating system to exist in a system reserved area on a disk drive this feature provides a Set Features function to temporarily offset the drive address space. The offset address space wraps around so that the entire disk drive address space remains addressable in offset mode. Max LBA in offset mode is set to the end of the system reserved area to protect the data in the user area when operating in offset mode. The Max LBA can be changed by an Set Max Address command to access the But any commands which access sectors across the original native maximum LBA are rejected with error, even if this protection is removed by an Set Max Address command.5.15.1 Enable/Disable Address Offset Mode Set Features subcommand code 09h Enable Address Offset Mode offsets address Cylinder 0, Head 0, Sector 1, LBA 0, to the start of the non-volatile protected area established using the Set Max Address command. The offset condition is cleared by Subcommand 89h Disable Address Offset Mode, Hardware reset or Power on Reset. If Reverting to Power on Defaults has been enabled by Set Features command, it is cleared by Soft reset as well. Upon entering offset mode the capacity of the drive returned in the Identify Device data is the size of the former protected area. A subsequent Set Max Address command with the address returned by Read Max Address command allows access to the entire drive. Addresses wrap so the entire drive remains addressable. If a non-volatile protected area has not been established before the device receives a Set Features Enable Address Offset Mode command, the command fails with Abort error status. Disable Address Offset Feature removes the address offset and sets the size of the drive reported by the Identify Device command back to the size specified in the last non-volatile Set Max Address command. Deskstar 7K400 Hard Disk Drive Specification 97

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Deskstar 7K400 Hard Disk Drive Specification
97
10.16
Address Offset Feature
Computer systems perform initial code loading (booting) by reading from a predefined address on a disk drive. To
allow an alternate bootable operating system to exist in a system reserved area on a disk drive this feature provides
a Set Features function to temporarily offset the drive address space. The offset address space wraps around so that
the entire disk drive address space remains addressable in offset mode. Max LBA in offset mode is set to the end of
the system reserved area to protect the data in the user area when operating in offset mode. The Max LBA can be
changed by an Set Max Address command to access the But any commands which access sectors across the original
native maximum LBA are rejected with error, even if this protection is removed by an Set Max Address
command.5.15.1 Enable/Disable Address Offset Mode
Set Features subcommand code 09h Enable Address Offset Mode offsets address Cylinder 0, Head 0, Sector 1, LBA
0, to the start of the non-volatile protected area established using the Set Max Address command. The offset
condition is cleared by Subcommand 89h Disable Address Offset Mode, Hardware reset or Power on Reset. If
Reverting to Power on Defaults has been enabled by Set Features command, it is cleared by Soft reset as well. Upon
entering offset mode the capacity of the drive returned in the Identify Device data is the size of the former protected
area. A subsequent Set Max Address command with the address returned by Read Max Address command allows
access to the entire drive. Addresses wrap so the entire drive remains addressable.
If a non-volatile protected area has not been established before the device receives a Set Features Enable Address
Offset Mode command, the command fails with Abort error status.
Disable Address Offset Feature removes the address offset and sets the size of the drive reported by the Identify
Device command back to the size specified in the last non-volatile Set Max Address command.