Specifications

ATAPI For Streaming Tape QIC-157 Rev B
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cleared in the Status Register to free the bus. The actual Completion Status is unknown until the
DSC bit in the Register Status is set. This delayed status is not a deferred error.
The deferred error may be indicated by returning “Check Condition” status to the Host as described
below. The subsequent execution of a REQUEST SENSE command shall return the deferred error
sense information. If an I/O Command terminates with “Check Condition” status and the subsequent
sense data returns a deferred error, that I/O command shall not have been executed. After the
Device detects a deferred error condition, it shall return a deferred error according to the rules
described below:
1. If a deferred error can be recovered with no external system intervention, a deferred error
indication shall not be set unless required by the error handling parameters of the MODE
SELECT command. The occurrence of the error may be logged if statistical or error logging is
supported.
2. If a deferred error can be associated with a particular function or a particular subset of data, and
the error is either unrecovered or required to be reported by the mode parameters, a deferred
error indication shall be returned to the Host.
Deferred errors may indicate that an operation was unsuccessful long after the command
performing the data transfer returned “Good” status. If data that cannot be replicated or recovered
from other sources is being stored using buffered write operations, synchronization commands
should be performed before the critical data is destroyed in the Host. This is necessary to be sure
that recovery actions can be taken if deferred errors do occur in the storing of the data.