Dell PowerVault TL2000 User Manual download pdf (Page 103)

No Operation

The NO-OP message is sent from an initiator to inform the target that no message is valid in response to

the target request for a message. The media changer does not take any action in response to the No

Operation message; it accepts this message and continues processing the current command.

Message Parity Error

The MESSAGE PARITY ERROR message is sent from the initiator to the target to indicate that one or

more bytes in the last message received contained a parity error.

Bus Device Reset

The BUS DEVICE RESET message is sent from an initiator to clear all commands, data, and status at the

target. When the target recognizes this message, it aborts the command currently being executed,

proceeds to the BUS FREE state and executes a soft reset.

Identify

The IDENTIFY messages are sent either by the initiator or by the target to establish (or reestablish) the

logical connection path between an initiator and target for a particular logical unit.

Bit 7 6 5 4 3 2 1 0

Byte

0 Identify DiscPriv LUNTAR Reserved LUN

Field Descriptions:

Bit 7 - Identify

This bit must be set to 1 to indicate this is the Identify message.

Bit 6 - DiscPriv (Disconnect Privlege)

This bit indicates whether the initiator supports the disconnect privelege, as follows:

v 0 - Disconnect is not allowed

v 1 - Disconnect is allowed

The

media changer always sets this bit to 0. Only initiators indicate if they support disconnect.

Bit 5 - LUNTAR (Logical Unit Target)

This bit indicates the LUNs that you can access on this device. This bit must be set to 0 to

indicate that the Identify message is directed to a logical unit.

Bit 2 ..0 - LUN (Logical Unit Number)

The only supported logical unit number for the media changer is 1. If the LUN fiels is set to a other

value than 0, the media changer returns Check Condition status to commands other than

INQUIRY and REQUEST SENSE, and the sense data is set to indicate that the logical unit is not

supported.

Chapter 4. Messages 4-3

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Dell PowerVault TL2000 User Manual Page 103