Enable/Disable Address Offset Mode; Identify Device Data; Figure 67. Device Address Map Before And After Set Feature - IBM DJSA-210 - Travelstar 10 GB Hard Drive Specifications

11.10.1 Enable/Disable Address Offset Mode

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 the 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.
– Before Enable Address Offset Mode
A reserved area has been created using a non-volatile Set Max command.
User Accessible Area
LBA 0
– After Enable Address Offset Mode
The former reserved area is now the user accessible area.
– After Set Max Address Command using the Value Returned by Read Max
Address

Figure 67. Device address map before and after Set Feature

11.10.2 Identify Device Data

Identify Device data, word 83, bit 7 indicates the device supports the Address Offset Feature. Identify
Device data, word 86, bit 7 indicates the device is in Address Offset mode.
Reserved Area
LBA R
User Accessible
Area (former
Reserved Area)
LBA 0
User Accessible Area
LBA 0
Travelstar 32GH/30GT/20GN hard disk drive specifications
LBA M
Reserved Area
(former User Accessible
Area)
LBA M–R
92
LBA M
LBA M