Read; Command Description - Tandberg Data SLR7-140 PROGRAMMER Manual

17.

Read

17.1. Command Description

The READ command transfers one or more blocks to the
Initiator beginning with the next block on the tape.
The Fixed (FIX) bit specifies both the meaning of the
Transfer Length
variable length block(s) are to be transferred. The data
read will be returned during the DATA-IN phase of the
command.
When the FIX bit is set to zero, the Drive is requested
to transfer a single variable length data block. The
Transfer Length specifies the block length in number of
bytes. The block length found on the tape is expected to
be equal to the specified block length.
When the FIX bit is set to one, the Drive is requested
to transfer a
Transfer Length
transfer. All the blocks are expected to be of the same
length. The length expected is the length reported by
the MODE SENSE command (the Block Size field of the
Block Descriptor List). Note that a FIX bit of one is
not legal when the Drive has been set into Variable
Block mode. Variable Block mode is in effect when the
Block Size field in the Block Descriptor List of the
MODE SELECT command is set to zero (000000h). See the
MODE SELECT command for further details.
If the requested Transfer Length is zero, the Drive will
transfer no data and the logical tape position will not
be changed. This will not be considered an error.
If the READ command is the first media access command
executed on a
operation will start from BOP. If the partition number
is not explicitly changed, the Drive will start reading
on partition zero. If the READ command follows an ERASE,
LOAD/UNLOAD (with
command, the read operation will also start from BOP.
Refer to the corresponding command description for the
partition number. If the READ command follows a LOCATE,
1
SPACE, VERIFY
operation will start with the next block on the tape.
Upon termination
logical tape position
(fixed or variable) read (end-of-media side).
If disconnection is allowed, the Drive will disconnect
when executing this command.
1
VERIFY is not supported by SLR7 and SLR140
17-1 Tandberg SLR Product Line SCSI Functional Specifications
field and whether
number of fixed
specifies the
newly inserted
Load bit set
or another READ
of a successful
will be
fixed-length
length blocks.
number of blocks
cartridge, the
to one) or
command, the
READ command,
after the last
or
The
to
read
REWIND
read
the
block