Technical Reference Manual
Page 21
Drive Operations
3
Functions of the Drive
This chapter describes certain operational aspects of the drive, including
discussions of:
•
drive operational modes
•
error correction
•
read error recovery
•
downloadable microcode
•
buffer management
Drive Operational Modes
For the purpose of defining power requirements the following modes have been
defined:
••
Read/Write Mode without seeking or head switching data is read from or
written to the disk continuously.
••
Seek Mode (40%) occurs when 1/3 stroke seeks are performed at a 40%
seek duty cycle. While the actuator is not in motion the drive is internally
reading sector information and data.
••
Random (100%) Seek occurs when the drive continously seeking to
random track locations without transfering any data. This condition does
not occur in an applications environment. Adequate cooling must be
provided when testing in this mode to ensure environmental limits are not
exceeded.
••
Idle Mode occurs when the drive is not reading, writing, or seeking. The
motor is up to speed and the Drive Ready condition exists. The actuator is
residing on the last-accessed track.
••
Standby Mode occurs when the motor is stopped and the actuator is
latched in the landing zone. The drive will enter Standby mode after power-
on reset if the Disable Spin jumper is installed or the DSPN bit in MODE
SELECT page 0 is set. A STOP UNIT command will also place a drive into
Standby Mode. The drive will spin up and go into Idle mode when a START
UNIT command is issued or on a timed basis by SCSI ID if the SDLY bit is
set in MODE SELECT page 0. Refer to the MODE SELECT and MODE
SENSE commands in the Eleventh Generation SCSI Interface Manual for
additional details.
••
Spin-Up Mode occurs while the drive's spindle motor is being spun up to
speed after initial power on or after exiting Standby Mode.
