Request Volume Element Address - B5h

Note: Request Volume Element Address B5h is only supported by Scalar i2000 and i6000 libraries.

The library returns element descriptors that match the request made through a SEND VOLUME TAG command. Each element address will only be reported once in response to a SEND VOLUME TAG request. Multiple REQUEST VOLUME ELEMENT ADDRESS commands may be used to retrieve all the elements. If no elements match the SEND VOLUME TAG request, or all elements have already been reported, the response will only contain the volume element address header.

This command is used to receive the results of a SEND VOLUME TAG command.

The REQUEST VOLUME ELEMENT ADDRESS CDB format is shown in the following table.

Table 1: REQUEST VOLUME ELEMENT ADDRESS CDB format

Bit

Byte

7

6

5

4

3

2

1

0

0

Op Code (B5h)

1

Logical Unit Number

VolTag

Element Type Code

2

Starting Element Address

3

4

Number of Elements

5

6

Reserved

7

:

9

Allocation Length

10

Reserved

11

Control
Field Description
Volume Tag (VolTag)

This field indicates whether the volume tag (bar code label) information should be returned. A value of one will return the labels, a value of zero will not.
Element Type Code

This field specifies the element types selected for the returned information, as shown in Table 2.
Starting Element Address

This field specifies the minimum element address to report. Only elements with an element type code specified by the Element Type Code field, and with an address greater than or equal to the starting element address will be reported. The starting element address must be a valid element address, but not have to be within the range specified by the Element Type Code field.
Number of Elements

This field specifies the maximum number of element descriptors to return. Only those descriptors that can be completely transferred within the allotted allocation length will be returned.
Allocation Length

This field specifies the byte length allowed for returned element descriptors. Only complete element descriptors are returned. The library returns element descriptors until one of the following conditions are met:

  • All available element descriptors have been returned
  • The number of element descriptors specified in the Number of Elements field have been returned
  • The number of bytes specified in the Allocation Length field have been returned
  • There is less allocation length space available than is required by the next complete element descriptor

Table 2: Element Type Code

Code

Selected Element Type

0000b (0)

All element types reported

0001b (1)

Medium transport element (accessor)

0010b (2)

Storage element

0011b (3)

Import/Export element

0100b (4)

Data transfer element (drives)

Element status data consists of an eight-byte header, followed by one or more element status pages (per element type). Each element status page consists of a header, followed by one or more element descriptor blocks. A complete response then looks like:

Element Status Header

Element Status Page Header (first element type)

Element Descriptor

…(more descriptors)…

Element Descriptor

…(more status pages)…

Element Status Page Header (next element type)

Element Descriptor

…

Element Descriptor

There are only up to four Element Status Pages, one for each element type. The element status pages are identical to those described for the READ ELEMENT STATUS command in Element Status Page (see Element Status Page).

One header is returned for each REQUEST VOLUME ELEMENT ADDRESS command. The format is shown in the following table.

Table 3: Element Status Header

Bit

Byte

7

6

5

4

3

2

1

0

0

First Element Address Reported

1

2

Number of Elements Available

3

4

Reserved

 Send Action Code (5h)

5

:

7

Byte Count of Report Available

Field Description
First Element Address Reported

This field indicates the lowest element address found that meets the CDB request.
Number of Elements Available

This field indicates the number of elements found that meet the CDB request.
Send Action Code This field contains the action code that was sent in the SEND VOLUME TAG command. The value is 5h.
Byte Count of Report Available

This field indicates the number of available element status bytes that meet the CDB requirements. The value does not include the eight-byte element status header, and is not adjusted to match the value specified in the Allocation Length field of the CDB. This facilitates first issuing a REQUEST VOLUME ELEMENT ADDRESS command with an allocation length of eight bytes in order to determine the allocation length required to transfer all the element status data specified by the command.

The element descriptors within each page are also the same as those described for READ ELEMENT STATUS in Element Descriptors (see Element Descriptors).