IBM DTCA-24090 Hard Drive Specifications - Page 155

Device Attributes Data Structure

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and will be aborted by the device (including the SMART Disable Operations subcommand), returning the error code as specified in Figure 100 on page 156. Any Attribute Values accumulated and saved to volatile memory prior to receipt of the SMART Disable Operations command will be preserved in the device's Attribute Data Sectors. If the device is re-enabled, these Attribute Values will be updated, as needed, upon receipt of a SMART Read Attribute Values or SMART Save Attribute Values command. 12.30.1.8 SMART Return Status (Subcommand DAh) This command is used to communicate the reliability status of the device to the host's request. Upon receipt of the SMART Return Status subcommand the device asserts BSY, saves any updated Attribute Values to the reserved sector and compares the updated Attribute Values to the Attribute Thresholds. If the device does not detect a Threshold Exceeded Condition, or detects a Threshold Exceeded Condition but involving attributes are advisory,the device loads 4Fh into the Cylinder Low register, C2h into the Cylinder High register, clears BSY, and asserts INTRQ. If the device detects a Threshold Exceeded Condition for prefailure attributes, the device loads F4h into the Cylinder Low register, 2Ch into the Cylinder High register, clears BSY, and asserts INTRQ. Advisory attributes never result in negative reliability condition. 12.30.2 Device Attributes Data Structure The following defines the 512 bytes that make up the Attribute Value information. This data structure is accessed by the host in its entirety using the SMART Read Attribute Values subcommand. All multi-byte fields shown in these data structures follow the ATA-3 specification for byte ordering, namely that the least significant byte occupies the lowest numbered byte address location in the field. Command Descriptions 147

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and will be aborted by the device (including the SMART Disable Operations subcommand), returning the
error code as specified in Figure 100 on page 156.
Any Attribute Values accumulated and saved to volatile memory prior to receipt of the SMART Disable
Operations command will be preserved in the device's Attribute Data Sectors. If the device is re-enabled,
these Attribute Values will be updated, as needed, upon receipt of a SMART Read Attribute Values or
SMART Save Attribute Values command.
12.30.1.8
SMART Return Status (Subcommand DAh)
This command is used to communicate the reliability status of the device to the host's request. Upon receipt
of the SMART Return Status subcommand the device asserts BSY, saves any updated Attribute Values to
the reserved sector and compares the updated Attribute Values to the Attribute Thresholds.
If the device does not detect a Threshold Exceeded Condition, or detects a Threshold Exceeded Condition
but involving attributes are advisory,the device loads 4Fh into the Cylinder Low register, C2h into the Cyl-
inder High register, clears BSY, and asserts INTRQ.
If the device detects a Threshold Exceeded Condition for prefailure attributes, the device loads F4h into the
Cylinder Low register, 2Ch into the Cylinder High register, clears BSY, and asserts INTRQ.
Advisory attri-
butes never result in negative reliability condition.
12.30.2
Device Attributes Data Structure
The following defines the 512 bytes that make up the Attribute Value information. This data structure is
accessed by the host in its entirety using the SMART Read Attribute Values subcommand. All multi-byte
fields shown in these data structures follow the ATA-3 specification for byte ordering, namely that the least
significant byte occupies the lowest numbered byte address location in the field.
Command Descriptions
147