Reset; Contingent Allegiance - Sun Microsystems storagetek sl500 Reference Manual

Reset

The library recognizes three types of resets. It implements the SCSI hard reset
alternative and the Bus Device Reset message. In addition, the library generates an
implicit reset when the library is powered on.
When a reset condition is detected, the library performs these actions:
Clears all I/O processes and discontinues any current command in progress.
■
Clears logical unit and element reservations, except for persistent reservations,
■
for all initiators.
Sets the parameters for mode page 1Dh to the saved values (or to the default
■
values if the saved values are in error).
Upon completion of a reset condition, the library generates a Unit Attention to all
initiators to indicate that a reset occurred.

Contingent Allegiance

The target—the library or a drive—generates a Contingent Allegiance Condition
for the initiator that caused the error after:
The target returns a Check Condition status because it has detected an error,
■
failure or other exception condition
An unexpected, optional disconnect occurs between the target and the initiator.
■
(In other words, the target unexpectedly returns to the Bus Free phase.)
When the target generates a Contingent Allegiance Condition, a series of activities
occurs:
The target preserves the sense data in case it is requested by the initiator.
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If the next command from the initiator to the target (following the Contingent
■
Allegiance Condition) is Request Sense, the target returns the sense data. If the
target receives any command other than Request Sense, the sense data is lost
and the target processes the command.
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Bus Conditions
Chapter 3 SCSI Bus Operations 21