1.6 Transport layer

TAG field

The drive checks for duplication of tags. If a tag is found to be duplicated in the SAS address of the port, the drive sends the ACK primitive to temporarily close the connection. Then, after re-establishing a connection, the drive reports the CHECK CONDITION status with the OVERLAPPED COMMANDS DETECTS error. At this time, the drive aborts processing of all the commands received from the SAS address of the port.

CRC field

When a CRC error is detected, the drive sends the NAK primitive, and discards the COMMAND frame.

Frame length

When the IU length is other than 28 bytes, the drive reports INVALID FRAME (Response Code=0x02).

Command queue count value

If the drive receives a command when the queue is full, the drive sends the ACK primitive to temporarily close the connection. Then, after re- establishing a connection, the drive reports the QUEUE FULL status.

LOGICAL UNIT NUMBER field

TASK ATTRIBUTE field

CDB field

Refer to Chapter 2, "Command Processing," and Chapter 4, "Command Specification."

Reserved field

The drive ignores the Reserved fields except the CDB field.

Management of the command queue count (supplementary explanation)

The maximum command queue count (the upper limit of the number of commands to be accepted) of a drive is 128. However, if the drive is a dual port drive and, for example, has already queued 128 commands at port A, the drive can receive another command at port B without causing the Queue full error. In other words, at least one command can be received at each port of the drive even when the drive is in the Queue full state.

C141-C013

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Fujitsu MBA3300RC, MBC2036RC, MBC2073RC, MBA3147RC, MBA3073RC specifications Transport layer