The SCSI Timeout value is server side configurable parameter. It is typically between 5 to 60 seconds.
The Operating System’s SCSI Layer sets a timer on each SCSI command. When this timer expires, the SCSI layer will quiesce the host bus adapter (HBA) and wait for all outstanding commands to either time out or complete.
Most commonly, Timeouts occur in one of the following conditions:
- A SCSI Command is timed out and aborted
- A SCSI device reset is attempted
- A SCSI bus reset is attempted. This may have an adverse effect on other devices sharing that SCSI bus.
- A SCSI host (bus adapter) reset is attempted. This is an attempt to re-initialize the adapter card associated with the SCSI device that has the timed out command.
What is a SCSI Status code?
A SCSI Status Code is used to determine the success or failure of an individual SCSI command. At the end of any command, the target returns a Status Code byte which should be one of the following:
02h CHECK CONDITION
04h CONDITION MET
18h RESERVATION CONFLICT
28h TASK SET FULL
30h ACA ACTIVE
40h TASK ABORTED
List Of Check Condition SCSI Status Codes
When the target returns a Check Condition in response to a command it is indicating that it has entered a contingent allegiance condition. This means that an error occurred when it attempted to execute a SCSI command. In FCP the Key Code Qualifier (KCQ) from the target is included in the response.
To translate from Virtual Wisdom, Status is the SCSI Status Code, Sense is the Key (or Sense Key), and Additional Sense is the ASC/ASCQ (Additional Sense Code/Additional Sense Code Qualifier) combination to provide the details of the check condition.
To interpret each SCSI Status code, see http://www.t10.org/lists/2status.htm
Steps to interpret SCSI Status Code
Step1: Check the SCSI Status Code : http://www.t10.org/lists/2status.htm
Step2: Check the SCSI Sense Key : http://www.t10.org/lists/2sensekey.htm
Step3: Determine ASC (Additional Sense Code) and ASCQ (Additional Sense Code Qualifier) http://www.t10.org/lists/asc-num.htm