Error Recovery; Synchronized Spindle Operation; Assembly Descriptions; Head/Disk Assembly - HP C2246 Technical Reference Manual

Error Recovery
If an error occurs while a Target is executing a queued command, the following error recovery
sequence is performed to ensure proper handling of any commands still in the queue:
1.
Target sends a Check Condition status to the current Initiator.
2. A Contingent Allegiance condition is established for the current Initiator. This means all
commands in the queue are suspended until the next command is received from the current
Initiator (normally a REQUEST SENSE command). Commands received from other
Initiators will be queued normally.
3. If QErr= 1 in the Control Mode Parameter Page OAh (refer to the Mode Select and Mode
Sense commands), all commands in the queue are aborted upon receipt of a command to
clearwhich clears the Contingent Allegiance condition. A Unit Attention condition with an
Additional Sense Key of Tagged Commands Cleared by Another Initiator is established for
all other Initiators that had commands in the queue.
4. Current Initiator sends the next command. If the next command is an untagged
REQUEST SENSE, it is executed immediately by the Target. If the next command is any
command other than an untagged REQUEST SENSE, error recovery is terminated and the
command is queued or rejected according to normal queuing procedures. .
5. The Contingent Allegiance condition is removed, and any commands still in the queue are
executed by the Target in a normal manner.
Synchronized Spindle Operation
Synchronized spindle operation (Master or Slave modes) is enabled via Mode Page 04H. Refer
to Table 2-2 {Chapter 2), and the Mode Sense/Mode Select command information (Appendix
A), for more details about implementing these functions.
Assembly Descriptions
The assemblies in the disk drive include the head/disk assembly (HDA) and the drive
electronics/controller printed-circuit assembly (PCA). The sealed HDA contains the
mechanical and electromechanical assemblies of the disk drive. The drive electronics/controller
P CA provides the SCSI interface and all electronic control over the HDA. The following
paragraphs describe the major functional components of each assembly.
Head/Disk Assembly
The head/disk assembly (HDA) contains disks, heads, an actuator assembly, head interface
circuits, atmospheric controls, vibration isolators, and a spindle assembly. A stainless steel
baseplate and cover provide the supporting structure for these parts. The entire assembly is
sealed and is not field repairable.
Disks
The disks are 3.5-inch (95 mm) diameter aluminum substrates with sputtered thin-film
surfaces. Data is stored on both surfaces of all disks except for one surface reserved for servo
information.
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