Exabyte VXA-2, Руководство по эксплуатации продукта, Страница: 50 / 90

40
P
RODUCT
M
ANUAL
1009541
Chapter 6 O
VERVIEW OF THE
C
OMMAND
P
ROTOCOL
S
TATUS
B
YTES
After the tape drive executes a command, it issues a status byte to the initiator
that indicates whether it performed the command successfully. Table 6-2
describes the four status bytes supported by the tape drive.
S
ENSE
K
EYS
When the tape drive returns Check Condition status to the initiator, the
initiator can issue a REQUEST SENSE (03h) command to receive information
about the error, exception, or abnormal condition. This information includes a
sense key, which describes the general error or change of state. Table 6-3
describes the sense keys supported by the tape drive. Refer to the VXA-2 Tape
Drive SCSI Reference for a detailed explanation of the information returned by
the REQUEST SENSE (03h) command.
Table 6-2 Status byte descriptions
Status byte Hex
value
Description
Good 00h Indicates that the tape drive successfully completed the operation.
Check Condition 02h Indicates that an error, exception, or abnormal condition has caused sense
information to be set. The initiator can issue a REQUEST SENSE command
to access this information.
Busy 08h Indicates that the tape drive is busy. This status is sent whenever the tape
drive is unable to accept a command from an initiator.
Reservation Conflict 18h Indicates that the tape drive is reserved for the exclusive use of another
initiator.
Table 6-3 Supported sense keys
Sense key
Hex
Value
Description
No Sense 0h Indicates that there is no specific sense key information to be reported.
Recovered
Error
1h Indicates that the last command completed successfully with some recovery
action performed by the tape drive. Details may be available by examining the
additional sense bytes and the information field.
Not Ready 2h Indicates that the tape drive does not contain a data cartridge or that the data
cartridge is not loaded. Operator intervention may be required to correct this
condition.
Medium
Error
3h Indicates that the command terminated with a non-recoverable error
condition that may have been caused by a flaw in the tape or an error in the
recorded data. The tape drive may also return this sense key if it is unable to
distinguish between a flaw in the tape and a specific hardware failure (sense
key 4h).