HP LTO 4 FC, LTO 4 SCSI, LTO 4 SAS manual New features in ACI, Backward compatibility

•Send SCSI with the following opcodes:

Log Select	Mode Sense	Read Attribute
Mode Select	Request Sense	Write Attribute

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

4.2can 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

4.1format 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

4.0compatibility 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:

HP LTO Ultrium 4 drives technical reference manual, volume 2: software integration 39 HP restricted