IBM IC25N020ATDA04 - Travelstar 20 GB Hard Drive Specifications page 186

13.33.1.7 S.M.A.R.T. Write Log Sector (subcommand D6h)
This command writes 512 bytes of data to the specified log sector.
The 512 bytes of data are transferred at a command and the Sector Count value shall be set to one. The
Sector Number must be set to specify the "log sector address" (see Figure 117 on page 171). If a Read
Only log sector is specified, the device returns an ABRT error.
13.33.1.8 S.M.A.R.T. Enable Operations (subcommand D8h)
This subcommand enables access to all S.M.A.R.T. capabilities within the device. Prior to receipt of a
S.M.A.R.T. Enable Operations subcommand, Attribute Values are neither monitored nor saved by the
device. The state of S.M.A.R.T. — either enabled or disabled — will be preserved by the device across
power cycles. Once enabled, the receipt of subsequent S.M.A.R.T. Enable Operations subcommands will
not affect any of the Attribute Values.
Upon receipt of the S.M.A.R.T. Enable Operations subcommand from the host, the device asserts BSY,
enables S.M.A.R.T. capabilities and functions, clears BSY, and asserts INTRQ.
13.33.1.9 S.M.A.R.T. Disable Operations (subcommand D9h)
This subcommand disables all S.M.A.R.T. capabilities within the device including the device's attribute
auto save feature. After receipt of this subcommand the device disables all S.M.A.R.T. operations. Non
self-preserved Attribute Values will no longer be monitored. The state of S.M.A.R.T. — either enabled or
disabled — is preserved by the device across power cycles. Note that this subcommand does not
preclude the device's power mode attribute auto saving.
Upon receipt of the S.M.A.R.T. Disable Operations subcommand from the host, the device asserts BSY,
disables S.M.A.R.T. capabilities and functions, clears BSY, and asserts INTRQ.
After receipt of the device of the S.M.A.R.T. Disable Operations subcommand from the host, all other
S.M.A.R.T. subcommands — with the exception of S.M.A.R.T. Enable Operations — are disabled, and
invalid and will be aborted by the device — including the S.M.A.R.T. Disable Operations subcommand —
returning the S.M.A.R.T. error code as specified in Figure 128 on page 185.
Any Attribute Values accumulated and saved to volatile memory prior to receipt of the S.M.A.R.T. 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 S.M.A.R.T. Read Attribute Values or
a S.M.A.R.T. Save Attribute Values command.
13.33.1.10 S.M.A.R.T. Return Status (subcommand DAh)
This subcommand is used to communicate the reliability status of the device to the host's request. Upon
receipt of the S.M.A.R.T. 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 a negative reliability condition.
Travelstar 48GH, 30GN & 15GN hard disk drive specifications
172