Data Transfer Element Descriptor - Sony LIB-D81 Product Description Manual

8.17.3. Data transfer element descriptor

The Source Storage Element Address area is set to the address of the Storage
Element where the media was before being moved. This area is valid when the
Svalid bit is 0.
The Primary Volume Tag Information area is provided to identify the media in
the Element. This area can be omitted in all Element Descriptor Blocks included
in the Element Status Page specified by PvolTag in the Element Status Page
header.
The Data transfer element descriptor is shown below.
Bit 7 6
Byte
0 (MSB)
1
2 Reserved
3
4
5
6 Not bus Reserved
7
8
9 SValid Invert
10 (MSB)
11
12
47
48
51
Table 8.17.3.1 : Data transfer element descriptor
An Access bit of 1 indicates that the tape drive can be accessed by the picker. A
bit of 0 indicates that the tape drive cannot be accessed by the picker. With this
autoloader, access is always possible, so it is always 1.
Notes
• During data transfer, access to the tape drive by the picker may be refused.
• Even when the value of this area is 1, access may not be successful. This bit
simply indicates whether the autoloader can mechanically access the tape
drive. It does not show the state of the tape drive.
A Not This Bus (not bus) bit of 1 indicates that the SCSI Bus Address and
Logical Unit Number of the SCSI bus selected by the autoloader are invalid. A
Not This Bus (not bus) bit of 0 indicates that the SCSI Address and Logical Unit
Number are from the same SCSI bus as the autoloader and are valid. Because
the SCSI bus and Data Transfer Element (Tape Drive) SCSI bus are inside the
autoloader, this is always 0.
An ID Valid bit of 1 indicates that the SCSI Bus Address value is valid. An LU
Valid bit of 1 indicates that the Logical Unit Number value is valid.
5 4 3
Element address
Access Except
Reserved
Additional sense code
Additional sense code qualifier
ID valid LU valid Reserved
SCSI bus address
Reserved
Reserved
Source storage element address
Primary volume tag information
(Field omitted if PVolTag = 0)
Reserved
(field moved up if Primary Volume
Tag Information field is omitted)
Chapter 8 SCSI Commands
2 1 0
(LSB)
Reserved Full
Logical unit number
(LSB)
125