IBM TS2900 Setup, Operator, And Service Manual page 244

SCSI sense data definition
The following example is of a tape drive communication failure while attached to an Open Systems host
through a SAS link, with SCSI protocol. When the host detected the failure, it built the following SCSI
Sense Data record. An explanation of the SCSI Sense Data breakout in this example follows.
SENSE DATA
aabb xxxx ccdd eeee eeee eeee eeee eeee ffgg hhxx ssss ssss ssss ssss ssss ....
0600 0000 1200 0000 0000 0000 0000 0000 0200 0300 0000 0000 0000 0000 0000 0000 0000
0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000
0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000
0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000
0000 0000 0000 0000 0000 0000 0000 0000 0000 0000
Note: The bold area represents the SCSI Sense Data that are presented by the host. The regular font data
(in this case many bytes of "zero"), designated by "ssss" would normally contain device sense data.
However, with the kind of failure in this example (COMMAND TIMEOUT), the host cannot collect valid
device sense data, so zeros are the result and are ignored. If the host was able to collect valid sense data
from the drive, the first byte "ss" would be "70", "71", "F0", or "F1", and valid device sense data would be
listed.
Detail Data
aabb xxxx ccdd eeee eeee eeee eeee eeee ffgg hhxx ssss ssss ssss ssss ssss ....
aa Length of the Command Descriptor Block (CDB) sent by the host.
In this case, "06" bytes.
bb SCSI target address. In this example, SCSI address "00".
xx Unused or reserved.
cc Start of CDB, cc is the operation code (byte 0). In this case,
"12" which was an "Inquiry".
SCSI sense data - library error
The following example of SCSI Sense Data was received from a System p Open System host and shows a
Tape Drive Failure and what the sense data would look like. Unlike the previous situation with "SCSI
sense data definition," this data contains valid sense data as defined by the hex "70" in the first sense
byte position. Therefore, instead of all zeros as in the previous example, there is valid data to rely on.
While the data shows a TAPE_ERR2, it might be caused by a library failure. When you attempt a Move
Medium command ("A5"), the ASC/ASCQ points to a "Mechanical Positioning Error". For more
information about sense data, see the IBM LTO Ultrium Tape Drive SCSI Reference.
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IBM TS2900 Tape Autoloader: Setup, Operator, and Service Guide Machine Type 3572