Table of Contents
Advertisement
SCSI Commands: 28BREAD
3.16.2.4
3.16.2.5
3.16.2.6
3.16.2.7
End of Medium (EOM) or End-of-Partition (EOP)
When the end-of-medium or end-of-partition position is encountered, the command
terminates with a Check Condition and Medium Error (03h) sense key. The Valid bit
(byte 0, bit 7) and the EOM bit (byte 2, bit 6) are set.
The Residual Length field is then set as follows:
If the Fixed bit is one, it equals the difference between the CDB transfer length and
the number of actual blocks read.
If the Fixed bit is zero, it equals the CDB transfer length.
The logical position after encountering an end-of-medium or end-of-partition error is
undetermined.
Recoverable Data Error
If an error is encountered while reading the drive applies its retry algorithm. If the
algorithm process cannot recover the error is reported as an unrecoverable read
error.
Unrecoverable Data Error
If an Unrecoverable Data Error is encountered, the READ command terminates with
Check Condition and a Medium Error (03h) sense key.
If the Valid bit (byte 0, bit 7) is one, Residual Length field equals the difference
between the requested Transfer Length and the actual number of blocks or bytes
transferred. On termination, the tape is positioned after the error block on the EOM
side of tape.
Incorrect Length
Writing fixed- and variable-length blocks vary according to the setting of the Fixed
bit.
When the Fixed bit is one, one or more tape blocks can be read. The CDB Transfer
Length field specifies the block count to read. The block size is the current block size
of the drive, which is set to 512 after a Bus Reset, Bus Device Reset message
(Parallel SCSI interface), Target Reset or Logical Unit Reset task management
request or Reset LIP (Fibre Channel interface), or power cycle.
The host can change the current block size by issuing a MODE SELECT command
with a new block descriptor parameter that specifies a new block size. If the current
block size differs from the actual block size of the block being read, the drive reports
an Incorrect Length error.
When the Fixed bit is zero, the CDB Transfer Length field indicates the number of
bytes to be read. When the actual block size found on tape differs from the CDB
Transfer Length, an Incorrect Length error is reported.
Page 125
Advertisement
Table of Contents
