Hitachi ULTRASTAR 15K450 HUS154530VLF400 - Manual (Page 334)

Hitachi Ultrastar 15K450 (FC-AL) Hard Disk Drive Specification
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The unit attention condition persists for each initiator until that initiator clears the condition from the logical unit as described
below. Several commands are handled as special cases during a unit attention condition These cases are also discussed below.
If the target receives a command from an initiator before reporting a CHECK CONDITION status for a pending unit attention
condition for that initiator, the target's response varies with the command as follows:
Inquiry Execute the command, return GOOD status, and preserve the unit attention condition.
Report Luns Same as above
Request Sense Execute the command, return any pending sense data, return GOOD status, and preserve the unit
attention condition. If there is not any pending sense data, the sense data associated with the highest
priority unit attention condition is returned and the highest priority unit attention condition is
cleared for this initiator.
All Others Do not execute the command, return a CHECK CONDITION status, clear the highest priority unit
attention condition for this initiator and return the associated sense data.
More than one unit attention condition may be generated for an initiator before that initiator clears the unit attention condition.