Quantum 10K II User Manual
Page 307
Feature Descriptions
6-6
Quantum Atlas 10K II Ultra 160/m SCSI Hard Disk Drives
6.11 COMMAND REORDERING
The drive uses Optimized Reordering Command Algorithm (ORCA) and tagged
command queuing to provide greater throughput by reordering any commands
queued on the drive to minimize rotational latency, seek time and head selection
time. The performance improvement is significant in heavily loaded applications
where queue depth exceeds 10-15 commands.
6.12 BANDED RECORDING
In banded recording, the disk is divided into multiple bands (also called partitions,
notches, or bit-zoned areas). Starting at the inner band, each band further out has
more blocks per track (a higher recording frequency). This use of multiple-frequency
recording increases the capacity of the drive.
6.13 SPECIAL FUNCTIONS
Quantum has incorporated a number of unique options into the drive. The
Quantum (Vendor) Special Function Control page is used to control these options.
The options include:
•
Initiate Synchronous Data Transfer Negotiation – a toggle-type parameter that
allows the initiator to move between asynchronous and synchronous modes of
data transfer.
•
Write Protect – Prevents writing to the disk drive.
•
Spin Delay – specifies if the drive should spin-up at power on or wait for a
START STOP UNIT command from the host.
•
Stagger Spin Delay – allows a series of drives to be spun up individually,
reducing the load on the system power supply.
6.14 POWER MANAGEMENT
The Quantum Atlas 10K II Ultra 160/m SCSI hard disk drives have three basic
power states:
•
OFF – power is removed from the drive.
•
UNIT READY – the drive is powered on and is ready to accept and execute
commands. A single sub-state of UNIT READY exists, ACTIVE. This is the
highest power consumption state of the drive. A media access command is acted
upon immediately by the drive.
The drive remains in the UNIT READY state.
•
NOT READY – The drive is powered on but cannot be addressed. An example of
this state is during spin-up. In other cases the drive may
require operator
intervention. This state will return a Status = Check condition.
The Power Condition Page, controlled with the MODE SELECT command, sets the
drive Power Management functions. This page is not changeable.