Seagate ST36421A, ST32112A manual 4 S.M.A.R.T. commands, Code in Features Register A.R.T. Command

30	U4 Family Product Manual, Rev. D
55H	Disable read look-ahead (read cache) feature.
82H	Disable write cache.
AAH	Enable read look-ahead (read cache) feature (default).

Note. At power-on, or after a hardware or software reset, the default values of the features are as indicated above.

3.2.4 S.M.A.R.T. commands

S.M.A.R.T. provides near-term failure prediction for disc drives. When S.M.A.R.T. is enabled, the drive monitors predetermined drive attributes that are susceptible to degradation over time. If self-monitoring determines that a failure is likely, S.M.A.R.T. makes a status report available to the host. Not all failures are predictable. S.M.A.R.T. predictability is limited to the attributes the drive can monitor. For more information on S.M.A.R.T. commands and implementation, see the Draft ATA-4 Standard.

This drive is shipped with S.M.A.R.T. features disabled. You must have a recent BIOS or software package that supports S.M.A.R.T. to enable this feature. The table below shows the S.M.A.R.T. command codes that the drive uses.

Code in Features
Register	S.M.A.R.T. Command
D0H	S.M.A.R.T. Read Data
D1H	Vendor-specific
D2H	S.M.A.R.T. Enable/Disable Attribute Autosave
D3H	S.M.A.R.T. Save Attribute Values
D4H	S.M.A.R.T. Execute Off-line Immediate
D7H	Vendor-specific
D8H	S.M.A.R.T. Enable Operations
D9H	S.M.A.R.T. Disable Operations
DAH	S.M.A.R.T. Return Status

Note. If an appropriate code is not written to the Features Register, the command is aborted and 0x04 (abort) is written to the Error register.