SCSI codes, also known as SCSI sense codes or sense key codes, are error codes returned by SCSI devices, including storage controllers, to indicate the reason for a specific SCSI command failure. Understanding these codes can be essential for troubleshooting storage-related issues in VMware environments. Below is a cheat sheet of common SCSI codes and their meanings:

Key/ASC/ASCQ: These fields represent the Sense Key, Additional Sense Code (ASC), and Additional Sense Code Qualifier (ASCQ), respectively. They are displayed in hexadecimal format.

1. 0x00/0x00/0x00: No Sense – Indicates that the command completed successfully without any errors.
2. 0x02/0x04/0x03: Not Ready – Logical Unit Not Ready, Format in Progress – The requested operation cannot be performed as the logical unit is undergoing a format operation.
3. 0x03/0x11/0x00: Medium Error – Unrecovered Read Error – The requested read operation encountered an unrecoverable error on the storage medium.
4. 0x04/0x08/0x03: Hardware Error – Timeout on Logical Unit – The command could not be completed due to a timeout on the storage device.
5. 0x05/0x20/0x00: Illegal Request – Invalid Command Operation Code – The command issued to the storage device is not supported or is invalid.
6. 0x06/0x28/0x00: Check Condition – Not Ready to Ready Transition – The logical unit transitioned from a Not Ready to Ready state, indicating a possible recoverable error.
7. 0x08/0x02/0x00: Busy – Initiator Process is Busy – The SCSI target is currently busy with another operation and cannot process the requested command.
8. 0x0B/0x03/0x00: Aborted Command – The command was aborted by the SCSI target due to an internal error or an external event.
9. 0x0D/0x00/0x00: Volume Overflow – The logical unit has reached its maximum capacity, and additional data cannot be written.
10. 0x11/0x00/0x00: Unrecovered Read Error – A read command resulted in an unrecoverable error on the storage medium.
11. 0x14/0x00/0x00: Record Not Found – The requested data record was not found on the storage medium.
12. 0x15/0x00/0x00: Random Positioning Error – A positioning command encountered an error in seeking the requested location on the storage medium.

It is important to note that SCSI codes can vary between different storage devices and vendors. Additionally, in VMware environments, SCSI codes may be translated into more user-friendly error messages in log files and error reports.

When troubleshooting storage-related issues in VMware, understanding these SCSI codes can help pinpoint the cause of failures and assist in resolving problems effectively.