Seagate ST3250823ACE, ST3200826ACE, ST3300831ACE manual Set Features command, 4 S.M.A.R.T. commands

4.1.3Set Features command

This command controls the implementation of various features that the drive supports. When the drive receives this command, it sets BSY, checks the contents of the Features register, clears BSY and generates an inter- rupt. If the value in the register does not represent a feature that the drive supports, the command is aborted. Power-on default has the read look-ahead and write caching features enabled. The acceptable values for the Features register are defined as follows:

02H	Enable write cache (default).
03H	Set transfer mode (based on value in Sector Count register).
	Sector Count register values:
	00H	Set PIO mode to default (PIO mode 2).
	01H	Set PIO mode to default and disable IORDY (PIO mode 2).
	08H	PIO mode 0
	09H	PIO mode 1
	0AH	PIO mode 2
	0BH	PIO mode 3
	0CH	PIO mode 4 (default)
	20H	Multiword DMA mode 0
	21H	Multiword DMA mode 1
	22H	Multiword DMA mode 2
	40H	Ultra DMA mode 0
	41H	Ultra DMA mode 1
	42H	Ultra DMA mode 2
	43H	Ultra DMA mode 3
	44H	Ultra DMA mode 4
	45H	Ultra DMA mode 5
55H	Disable read look-ahead (read cache) feature.
82H	Disable write cache.
AAH	Enable read look-ahead (read cache) feature (default).
F1H	Report full capacity available

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

4.1.4S.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 moni- tors 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-7 Standard.

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