Primary volume tag field, Medium transport element descriptor, Table 61 primary volume tag field – Dell PowerVault ML6000 User Manual
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SCSI Commands
Primary Volume Tag Field
Volume tags (returned in the Primary Volume Tag field) are basically barcode labels on the media. The
library supports labels from 5 to 16 characters in length. The Primary Volume Tag field contains 32 bytes of
label data (space filled to 32 bytes), followed by two reserved bytes, then two bytes of volume sequence
number. The library returns zeros for the last four bytes of Primary Volume Tag data.
If the user has configured the library to support media identification, media identifiers will be reported as
found on the barcode labels as part of the volume tag. If this feature is not enabled, any media identifiers
found will not be reported.
Medium Transport Element Descriptor
Element Address – This field contains the element address of the accessor.
Except – This field is set to 1 if the element is in an abnormal state. Additional information will be available
in the Additional Sense Code and Additional Sense Code Qualifier fields. This field is set to 0 if the element
is in a normal state.
Full – This field is set to 0 if the element does not contain media. It is set to 1 if it does. Since the medium
transport element cannot be a destination element, this field should normally return 0. There may be error
situations where media is left in the picker, which would be indicated by this field. In the case of dual pickers,
differentiation of state will be provided through the Additional Sense Code and Additional Sense Code
Qualifier fields when exception conditions are present (such as stranded media).
Additional Sense Code – If the element is in an abnormal state (no error or exception associated with it),
this field will be set to a value as described in
Table 61
Primary Volume Tag Field
Bit
Byte
7
6
5
4
3
2
1
0
0
Element Address
1
2
Element Descriptor Length
Except
Rsvd
Full
3
Reserved
4
Additional Sense Code
5
Additional Sense Code Qualifier
6
Reserved
8
9
Svalid
Invert
Reserved
10
Source Storage Element Address
11
12
Primary Volume Tag Information
(Field omitted if PVolTag = 0; remaining fields move up)
47
48
Reserved
51