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Page 118
VERIFY
Command Descriptor Block
Field Descriptions
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.
Bits
Byte
7
6
0
1
Ignored LUN
2
3
4
5
Field
Bytes
Bits
Operation
0
Code
Ignored
1
5-7
Logical
Unit
Fixed
1
0
Verify
2-4
Length
Reserved
Control
5
5
4
3
Operation Code (13h)
Reserved
Verification Length, MSB
Verification Length
Verification Length, LSB
Control
Description
The Operation Code for Verify is 00h.
The LUN field is residual from the SCSI-1 days and is ignored.
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
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.
All reserved bits must be 0.
The control field must be 0.
LTO SCSI Interface Manual
2
1
0
Fixed
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