IBM DTLA-305040 Hard Drive Specifications - Page 106

Address Offset Feature, 15.1 Enable/Disable Address Offset Mode

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3. Automatic Acoustic Management is enabled and the associated algorithm indicates that the Standby mode should be entered to reduce acoustical emanations. The IDENTIFY DEVICE response word 83, bit 9 indicates that Automatic Acoustic Management feature is supported if set. Word 86, bit 9 indicates that Automatic Acoustic Management is enabled if set. Word 94, bits 7-0 contain the current Automatic Acoustic Management level if Automatic Acoustic Management is enabled, and bits 8-15 contain the Vendor's recommended AAM level. 10.15 Address Offset Feature Computer systems perform initial code loading (booting) by reading from a predefined address on a drive. To allow an alternate bootable operating system to exist in a system reserved area on a 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 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 user area. If the native MAX LBA is set, the whole user area can be accessed. 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. 10.15.1 Enable/Disable Address Offset Mode The Set Features subcommand code 09h Enable Address Offset Mode offsets address Cylinder 0, Head 0, Sector 1, LBA 0, to the start of the nonvolatile 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 nonvolatile 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 nonvolatile Set Max Address command. Deskstar 40GV & 75GXP hard disk drive specifications 94

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3.
Automatic Acoustic Management is enabled and the associated algorithm indicates that the
Standby mode should be entered to reduce acoustical emanations.
The IDENTIFY DEVICE response word 83, bit 9 indicates that Automatic Acoustic Management feature
is supported if set. Word 86, bit 9 indicates that Automatic Acoustic Management is enabled if set. Word
94, bits 7-0 contain the current Automatic Acoustic Management level if Automatic Acoustic Management
is enabled, and bits 8-15 contain the Vendor's recommended AAM level.
10.15 Address Offset Feature
Computer systems perform initial code loading (booting) by reading from a predefined address on a drive.
To allow an alternate bootable operating system to exist in a system reserved area on a drive, this feat-
ure provides a Set Features function to temporarily offset the drive address space. The offset address
space wraps around so that the entire 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 user area. If the native MAX LBA is set, the whole user area can be accessed. But any com-
mands 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.
10.15.1 Enable/Disable Address Offset Mode
The Set Features subcommand code 09h Enable Address Offset Mode offsets address Cylinder 0, Head
0, Sector 1, LBA 0, to the start of the nonvolatile 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 com-
mand, 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 com-
mand 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 nonvolatile 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 nonvolatile Set Max Address command.
Deskstar 40GV & 75GXP hard disk drive specifications
94