HP LTO 4 SCSI, LTO 4 FC, LTO 4 SAS Treatment of reserved fields, Recommended power-up sequence

Table 1 Non-queued ACI commands
ACI Command	Recommended time-out value
Get Drive Info	5s
Get Drive Status	5s
Get Drive Configuration	5s
Get Error Info	5s
Get Buffer Size	5s
No Op	5s
Acknowledge Attention	5s

Table 2 Queued ACI commands
ACI Command	Recommended time-out value
ACI Load—immediate	5s
ACI Load—non-immediate (drive idle, unloaded)	300s
ACI Unload—immediate	5s
ACI Unload—non-immediate (tape loaded, at EOM,	300s or 9000s depending on
drive idle)	implementation strategy
Set Drive Configuration (tape loaded, at EOM, SCSI	300s or 9000s depending on
unload)	implementation strategy
ACI Reset—ACI bus	5s
ACI Reset—drive	5s
Set Baud Rate	5s

Treatment of reserved fields

To ensure forwards compatibility with future versions of the ACI, automation controller firmware should set any command fields labelled as ‘Reserved’ to zero. Likewise, automation controller firmware should mask off any response fields labelled as ‘Reserved’ during the processing of tape drive responses. This will allow older versions of automation controller firmware to operate successfully with newer versions of tape drive firmware.

Recommended power-up sequence

After power-up, HP recommends that the automation controller wait until it has received at least one ASCII <ENQ> character from the tape drive before attempting a command-response transaction. HP Ultrium tape drives use a two-step power-up sequence and the drive sends <ENQ> to signal the transition between the steps. The drive sends the first <ENQ> within 500 milliseconds of exiting the reset state after receiving power. Note that the default baud rate at power-up is 9600.

Consider sending Get Drive Info as the first command, either packetized or primitive. This retrieves a variety of useful identifying information identifying the tape drive, including the version of the ACI protocol that the tape drive supports.

HP LTO Ultrium 4 drives technical reference manual, volume 2: software integration 43 HP restricted