Page
118
LTO SCSI Interface Manual
VERIFY
The Verify command verifies one or more blocks of data beginning with the next
block from the tape unit.
The command terminates after the specified number of bytes or blocks are verified
or when the drive encounters a filemark, the EOD, the EOT, or an unrecoverable
error. On completion the medium is positioned after the last block verified, after the
end-of-data, after a filemark or after an unrecoverable block.
If a Verify with a zero verification length is issued, no data is verified, and the current
position on the tape does not change. This condition is not considered an error.
The Verify command causes data to be read from the tape and passed through the
drive’s error detection and correction hardware to determine whether it can be
recovered from the tape. The amount of data to be read is indicated by the
Verification Length field and the Fixed flag in the same manner as is used in a Read
command.
Command Descriptor Block
Byte
Bits
7
6
5
4
3
2
1
0
0
Operation Code (13h)
1
Ignored LUN Reserved
Fixed
2
Verification Length, MSB
3
Verification Length
4
Verification Length, LSB
5
Control
Field Descriptions
Field
Bytes
Bits
Description
Operation
Code
0
The Operation Code for Verify is 00h.
Ignored
Logical
Unit
1
5-7
The LUN field is residual from the SCSI-1 days and is ignored.
Fixed
1
0
0 = Variable block length. Verify Length contains the number of
bytes to return.
1 = Fixed block length, as specified by the MODE SELECT Block
Descriptor. Verify Length contains the number of blocks to re-
turn
Verify
Length
2-4
This field specifies the number of bytes (Fixed = 0) or blocks (Fixed
= 1) to be verified. A transfer length of 0 is valid and no data is veri-
fied.
Reserved
All reserved bits must be 0.
Control
5
The control field must be 0.
