HP LTO Ultrium 4 drives technical reference manual, volume 2: software integration 39
HP restricted
• Send SCSI with the following opcodes:
New features in ACI 4.3
The following sections describe the differences between revision 4.2 of the ACI specification, used
in HP LTO Ultrium 3 drives, and revision 4.3, used in HP LTO Ultrium 4 tape drives.
The main additions to ACI 4.2 revision are:
• Improved backward compatibility
• Support for encryption
Backward compatibility
To provide backward compatibility with ACI 4.0, SCSI parallel drives initialize in ACI 4.0
compatibility mode. Similarly, Fibre Channel drives initialize in ACI 4.1 compatibility mode and
SAS drives initialize to ACI 4.2 compatibility mode. This means drives with ACI 4.0, ACI 4.1 or ACI
4.2 can be replaced with drives with ACI 4.3, without the need to replace or update the automation
controller firmware.
• In ACI 4.0 compatibility mode the drive will accept Set Drive Configuration CMD_DATA in ACI
4.0 format and will respond to Get Drive Status and Get Drive Configuration with ACI 4.0
RDATA.
• In ACI 4.1 compatibility mode the tape drive will accept Set Drive Configuration in ACI 4.1
format and will respond to Get Drive Status and Get Drive Configuration with ACI 4.1 RDATA.
• In ACI 4.2 compatibility mode the tape drive will accept Set Drive Configuration in ACI 4.2
format and will respond to Get Drive Status and Get Drive Configuration with ACI 4.2 RDATA.
An ACI compatibility mode does not restrict the use of ACI 4.3 commands or the use of new fields
to earlier ACI version commands and will respond with the appropriate ACI 4.3 RDATA in these
cases.
• A parallel SCSI tape drive will remain in ACI 4.0 compatibility mode until it receives a valid ACI
4.1 format Set Drive Configuration command or an ACI 4.2/4.3 format Set Drive Configuration
command with the ACI Major/Minor Version fields set to a new and valid ACI version (which is
42h). It will then respond with the appropriate ACI version RDATA. The drive will return to ACI
4.0 compatibility mode in the following circumstances:
• If the tape drive receives a valid ACI 4.0 format Set Drive Configuration command.
• An ACI 4.2 or ACI 4.3 format Set Drive Configuration command with the ACI Major/Minor
Version fields set to 40h.
• The tape drive is reset.
• A Fibre Channel tape drive will remain in ACI 4.1 compatibility mode until it receives a valid
ACI 4.2/4.3 format Set Drive Configuration command with the ACI Major/MinorVersion fields
set to a new and valid ACI version (which is 42h). It will then respond with the appropriate ACI
version RDATA. The drive will return to ACI 4.1 compatibility mode in the following
circumstances:
Log Select Mode Sense Read Attribute
Mode Select Request Sense Write Attribute
